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Adatom Diffusion. Mass transport driven by the temperature gradient is well known in gases and liquids, as fluids can readily undergo mass transport via convection or Soret diffusion 1,2. LAMMPS is updated continuously. His papers on diffusion came from his Ph. At high concentration, there is a second peak observed at around 7 Å, likely present due to the high concentration in the bulk. Article describing spin-AM05: PRB 79, 155101 (2009). You can reset the image flags (e. For T > 100 K thermal conductivity is practically independent of N. Examples: compute 1 all msd compute 1 upper msd com yes (MSD) versus time is proportional to the diffusion coefficient of the diffusing atoms. In the Stash, double-click on the “(5,5) Carbon Nanotube” object. 15 m/s at 180 K Interface velocity divided by the average self diffusion constant. An example of the complexity of the reaction mechanisms is shown in ﬁgure 5, where an annealing event. 7 implementations of a Bayesian implementation of the weighted histogram analysis method (WHAM) to estimate free energy surfaces (FES) from biased sampling data. If the medium is large and homogeneous, we get a host of coherent nonlinear phenomena such as Second Harmonic Generation (SHG), Coherent Anit-Stokes Raman Scattering (CARS), and more, in which the re-radiated light goes off in a single, well-defined direction. The purpose of this document is to provide a practical introduction to the simulation of molecules in LAMMPS. Following the maximum. Using this protocol, the resulting diffusion coefficients were close to the ones obtained starting the workflow from PFF simulations, as shown on the right of Figure 6. This problem is overcome by creating very long bonds in the polymerization stage, and then relaxing these to equilibrium values by using a directed‐diffusion‐based relaxation strategy. See below for a thorough description of how the model is specified to LAMMPS. The MedeA-Morphology module takes as input a crystal structure and uses the supplied cell dimensions and crystal symmetry to compute the standard Bravais, Friedel, Donnay and Harker (BFDH) crystal morphology based on interplanar spacings for low index crystal faces. OLCF 2024 Roadmap We have increased our systems capability at our center since 2004 by a factor of 10,000X We are currently at 27PF, however the Exascale reports have pointed out that systems will be required at the level of 1 EF and beyond in order to reach critical DOE science goals Our facilities plan therefore is to deploy a system of up to. Other workers use diffuse electron density [] or polarizable versions of the non-polarizable models, using flexible bonding (for example, SWFLEX-AI), induced dipoles (for example, []), energy optimization (for example, the TIP4P-FQ version of TIP4P) or movable charge (for example, SWFLEX-AI), all of which generally give better. Howto discussions. As the ReaxFF-GUI is very similar to the ADF-GUI, we will focus here on ReaxFF specific features. Lecture 5: Diffusion Coefficient (Diffusivity) Today's topics • Understand the general physical meaning of diffusion coefficient. 1 gives such examples of some physical quantities of interest in LJ units and in SI units (for the case in which the bead is the CH 2 unit of polyethylene or a possible group of polymer. Most of the papers listed discuss simulation results generated with LAMMPS, but some describe other codes or algorithms and may only cite LAMMPS in passing. Metadynamics Simulation of Cu Vacancy Diffusion on Cu(111) - Using PLUMED Determination of low strain interfaces via geometric matching Open-circuit voltage profile of a Li-S battery: ReaxFF molecular dynamics. The work is in the exploratory stages and we will only present some preliminary results. 608 × 10 −40 F·m 2. This includes the 5. 16 The library header files are installed in a subdirectory gsl of the main installation directory that must prefix preprocessing include statements, see e. Google Sites. Examples: app_style potts/strain 100 See app_style diffusion for an Ising model which performs Kawasaki dynamics, meaning the spins on two neighboring sites The "couple" directory of the LAMMPS molecular dynamics package includes a sample coupled LAMMPS/SPPARKS application which uses LAMMPS to compute strain values at each site of a. NASA Astrophysics Data System (ADS) Ferri, S. Here we show that density-based clustering of the trajectories computed using molecular dynamics. GPU Acceleration of Molecular Modeling Applications Modern graphics processing units (GPUs) contain hundreds of arithmetic units and can be harnessed to provide tremendous acceleration for numerically intensive scientific applications such as molecular modeling. LAMMPS (Large-scale Atomic/Molecular Massively Parallel Simulator) is a classical molecular dynamics simulation tool that is able to exploit modern parallel computing environments such as the cloud environments provided by Amazon and Microsoft. The purpose of this Case Study is to demonstrate how one computes a self-diffusion coefficient, , from an MD simulation of a simple Lennard-Jones liquid. LAMMPS 1, the Sandia National Laboratories 'Large-scale Atomic/Molecular Massively Parallel Simulator' , provides impressive molecular dynamics performance, particularly when coupled with modern parallel-friendly compute environments. zip contains an example equilibration for a UO 2 super-cell with the fluorite structure. The displacement of an atom is from its original position at the time the compute command was issued. changed to execute sftp test automatically if sftp test is not executed at least once when executing remote job submission. The diffusive mass flux of each species is, in turn, expressed based on the gradients of the mole or mass fractions, using multi-component diffusion coefficients D ik. This example shows how to solve the heat equation with a temperature-dependent thermal conductivity. May 9, 2013 • LAMMPS • IMD • other • Example: fcc phase in steels can be referred to as fcc, austenite or γ. Yes, there is, it has been done by others. Erickson, Steven J. diffusion coefficients in LAMMPS. We studied grain boundary (GB) self-diffusion in body-centered cubic iron using ab initio calculations and molecular dynamics simulations with various interatomic potentials. 2 (in our units, nm^2 / ps), so in the simulation it can be slightly bigger or less. LAMMPS trajectories into QuantumATK. The development of Gromacs would not have been possible without generous funding support from the BioExcel HPC Center of Excellence supported by the European Union Horizon 2020 Programme, the European Research Council, the Swedish Research Council, the Swedish Foundation for Strategic Research, the Swedish National Infrastructure for Computing, and the Swedish Foundation for International. Examples: compute 1 all msd compute 1 upper msd com yes (MSD) versus time is proportional to the diffusion coefficient of the diffusing atoms. where M i is the relative molar mass (kg mol-1) of species i. Open Access Dissertations. It comes with state-of-the-art tools for 3D rendering, a suite of widgets for 3D interaction, and extensive 2D plotting capability. potential, Al99. Select the package you want via the circular check-button, click the "Download Now" button, and your browser should download a gzipped tar file. VII this result using the Green-Kubo relation is compared to the results of a previous experiment using a hydrodynamical method [31]. The diffusion. dat command. Open Access Dissertations. This in turn might reduce the friction felt by the rest of the water, hence increasing the rate of flow. Atomistic Simulation Of Plasma Interaction With Plasma Facing Components In Fusion Reactors Xue Yang Purdue University Yang, Xue, "Atomistic Simulation Of Plasma Interaction With Plasma Facing Components In Fusion Reactors" (2013). This input script was run using the Aug 2015 version of LAMMPS. His papers on diffusion came from his Ph. In particular, the diffusion jump barrier looks like $$\omega_0 = u_0^\star \exp(-H_\mathrm{m} / k_\mathrm{B} T)$$, where $$u_0^\star = \prod_{i=1}^{3N-3} u_i^\mathrm{IS} / \prod_{i=1}^{3N-4} u_i^\mathrm{TS}$$, with IS and TS indicating the initial and transition. Erickson, Steven J. It includes the many-body DPD (mDPD) model for multiphase problems, the energy-conserving DPD (eDPD) model for non-isothermal dynamics, and the transport DPD (tDPD) for mesoscopic problems involving advection-diffusion-reaction processes. For example, the computed diffusion constants for particles would give erroneous values. Adaptively Restrained Molecular Dynamics (ARMD) is a recently. Example problems. Heat will cause the gas pressure to increase, which may open the relief valve and allow gas to escape. As the ReaxFF-GUI is very similar to the ADF-GUI, we will focus here on ReaxFF specific features. The wave pulse is a product of Sin(2*PI*q*dt) and Cos(2*PI*q*dt) function. Howto discussions. > > Where am I to input parameters for bond-angle and bond-bond interaction > terms in LAMMPS? as class2 angle parameters. of Materials Science & Engineering, University of Tennessee, Knoxville for example pressure gradient, a giving rise to a density. A quick tutorial on how to use simple thermostats and model a diffusion process with the molecular dynamics code LAMMPS. 94e−4 and 8. 134 eV from analyzing the Arrhenius Plot formed by the diffusion coefficients at various temperatures up to near the thermal breakdown temperature. Users are encouraged to download and use interatomic potentials, with proper acknowledgement, and developers are welcome to contribute potentials for inclusion. The Stillinger-Weber potential file must contain entries for all the elements listed in the pair_coeff command. in # Reference: Physical Chemistry Chemical Physics, 16(13) (2014):6233-6249. The files for this example are contained in the directory Example2. The solid curve is the best-fit Cauchy-Lorentz distribution with zero mean velocity, v o ¼ 0, and FWHM 2Γ: Lðv;ΓÞ¼ 1=πΓ 1þ½ðv −v oÞ=Γ 2: ð1Þ. LAMMPS User Documentation. out Description: Use a two-temperature model (TTM) to represent heat transfer through and between electronic and atomic subsystems. 33e−3 molecule/Å 3. Introduction; 2. To run the test, change directory to this folder and type make". Example problems The LAMMPS distribution includes an examples sub-directory with several sample problems. Tschopp, Email me Please contact me if you have any questions or comments about the tutorials. I got a plot like (attached) this 'MSD vs time' using LAMMPS. 6 nanoseconds but it. *) and produces a log file (log. • What is chemical diffusion coefficient (D. Steve Plimpton and his team , LAMMPS focuses on the efficient execution of computational tasks. 63 kcal/mol on 80+ reactions from the G2 set) (to be published). Latest: MgY. Each problem is in a sub-directory of its own. LAMMPS input files This page makes various LAMMPS input files available for download. Compute Canada / WestGrid. LAMMPS is a classical molecular dynamics code, and an acronym for Large-scale Atomic/Molecular Massively Parallel Simulator. Author summary Three-dimensional genome organization is expected to play crucial roles in regulating gene expression and establishing cell fate, and has inspired the development of numerous innovative experimental techniques for its characterization. Atom before diffusion Atom after diffusion Self diffusion (motion of atoms within a pure host) also occurs. example of NVT equilibration in LAMMPS All the simulation was carried out in the NVT ensemble. Diffusion occurs in various systems. This allows the diffusion coefficient to be estimated on-the-fly using variables in the LAMMPS input scripts. (University of La Plata), M. Users are encouraged to download and use interatomic potentials, with proper acknowledgement, and developers are welcome to contribute potentials for inclusion. 0 2 z 100 100 2 couple none drag 1. 6 nanoseconds but it. Self-Diffusion Coefficients. I started with LAMMPS's example script which uses LJ units. A physically realistic model, depending on the system at hand and the questions asked, would require different levels of modeling detail such as particle diffusion, geometrical confinement, particle volume exclusion or. MedeA-Phonon is based on the work by Prof. So there is a thermo style in lammps which allows the mass density of the entire cell to be calculated automatically. Computational Rheology via LAMMPS, October 12, 2013 85th Meeting of the Society of Rheology 5: Atomistic Applications with LAMMPS J. The dependence of thermal conductivity K versus doping level N at 20K. A)? How are they inter-related Das. For better statistics you typically want to use multiple time origins, post-processing the data from dump files. This includes time integration (update of coordinates and velocities), force constraints or boundary conditions (SHAKE or walls), and diagnostics (compute a diffusion coefficient). Dual boot Linux/Windows; 2. to study diffusion of a methane (CH) molecule in a silica zeolite (SiO). 2d simulations. 63 kcal/mol on 80+ reactions from the G2 set) (to be published). , for the U. 1-2: 3-atom linear chain diffusion along the edge; generation of Pd adaatom and surface vacancy. txt (not the same as viewing the source of the HTML file). Self-Diffusion Coefficients. diffusion coefficients in LAMMPS. The notes begin with some formal theory and conclude with practical implementation. Knowing this fundamental physical quantity is needed to understand liquid dynamics, as well. The critical step is to melt the ice slowly. When you specify the residuals you might also want to increase the stop time to a lot higher value, for example 10 000. Diffusion lammps (master) Edit. cpp is a simple example of setting forces on atoms to prescribed values. USim for High Energy Density Plasmas examples and documentation, demonstrating independent evolution of ions and electrons, coupling of ions, electron fluids, and electromagnetic fields, as well as general equation of state for ions and electrons, reduce your learning curve and ensure faster results. micelle script. 0 3 all npt temp 300 100 0. of Manitoba, Winnipeg. Example 3-5: Training and MD. Make the simulation box periodic in z via the boundary command. 1-3 weight percentage of nano graphene to EPON 862 polymer and an analytical model for moisture diffusion in presence of nano graphene was derived assuming time-dependent diffusivity and moisture boundary conditions. ERIC Educational Resources Information Center. Migration barriers for surface diffusion on a rigid lattice: Challenges and solutions. LAMMPS Documentation 30 Oct 2014 version Version info: The LAMMPS "version" is the date when it was released, such as 1 May 2010. changed to execute sftp test automatically if sftp test is not executed at least once when executing remote job submission. Meaning: Masses for each type of species. The liquid-vacuum interface of molten alkali carbonate salts is studied with molecular dynamics simulations. Temperature dependent structure and dynamics in smectite interlayers: 23 Na MAS NMR spectroscopy of Na-hectorite† Raju Nanda * ab, Geoffrey M. Molecule Simulator. Burton d and R. html suffix of the URL you are browsing to. A physically realistic model, depending on the system at hand and the questions asked, would require different levels of modeling detail such as particle diffusion, geometrical confinement, particle volume exclusion or. Grenoble Alpes, LJK, F-38000 Grenoble, France 3 CNRS, LJK, F-38000 Grenoble, France E-mail: stephane. alloy; Save this in the same directory as the LAMMPS executable. Contact: Mark A. 1 and temperature T = 1. Three salts comprised of LixNayKzCO3 near their respective eutectic concentrations are considered to understand the distribution of ions relative to a liquid-vacuum interface and their diffusivity. The whole implementation is consistent with the parallel scheme employed in LAMMPS. Thus, for each MD time step, we performed ten electronic heat conduction steps. mv ${NAME} lammps_erase rm -rf lammps_erase & fi. Fast diffusion of water nanodroplets on graphene. Diffusion occurs in various systems. bench benchmark problems couple code coupling examples using LAMMPS as a library doc documentation examples simple test problems lib libraries LAMMPS can be linked. Calculations of Time Correlation Functions In the last chapter, we explored the low-frequency, long-wavelength behavior of a system that is disturbed from equilibrium. Michael Brown Prepared by Sandia National Laboratories Albuquerque, New Mexico 87185 and Livermore, California 94550. LAMMPS trajectories into QuantumATK. David Keffer. • Interstitial diffusion (depends on temperature). In LAMMPS, pair potentials are defined between pairs of atoms that are within a cutoff distance and the set of active interactions typically changes over time. /example2_fit_sin_with_nn/ python Fitting+sine+curve. It includes potentials for solid-state materials (metals, semiconductors) and soft matter (biomolecules, polymers) and coarse-grained or mesoscopic systems. of Materials Science & Engineering, University of Tennessee, Knoxville for example pressure gradient, a giving rise to a density. LAMMPS is a classical molecular dynamics code, and an acronym for Large-scale Atomic/Molecular Massively Parallel Simulator. The LAMMPS distribution includes an examples sub-directory with many sample problems. Multi-steps method for Navier-stokes equations with strongly nonlinear diffusion I am trying to solve a particular form of the Euler / Navier-Stokes equations in 1D, with very strong and non-linear diffusion coefficients. Implicit Radiation Solver for diffusion equation on a block structured mesh. But, I'm not sure if it yields thermal conductivity in W/m-K units. What I did was. TEM images of high burn-up fuel pellets show that the dislocations are heavily decorated by ﬁssion product precipitates, including in the LAMMPS simulation package [33]. Here are a few tutorials to get started using LAMMPS. 1, 2016, 2018, and 2019 release series. the example program blas_test. New styles can be created to add new options to LAMMPS. Start a command shell, navigate to the gas folder (e. Types of Diffusion Coefficients. So what the hell does that mean? for example. If tol = 0. Offered to B. LAMMPS has potentials for soft materials (biomolecules, polymers) and solid-state materials (metals, semiconductors) and coarse-grained or mesoscopic systems. hoffmann at asu. Molecular dynamics simulations of the effects of vacancies on nickel self-diffusion, oxygen diffusion and oxidation initiation in nickel, using the ReaxFF reactive force field Acta Materialia, Volume 83, 15 January 2015, Pages 102-112. Introduction to Molecular Dynamics Simulations using LAMMPS. For this example we require a hexagonal network to represent the cytoskeleton network which is not trivial to be done in the LAMMPS input script. The study of systems in. for example Chapters 7 and 8 (especially Table 8. 0 5 all npt temp 200 500 0. This includes time integration (update of coordinates and velocities), force constraints or boundary conditions (SHAKE or walls), and diagnostics (compute a diffusion coefficient). *) when it runs. COMSOL Multiphysics is a simulation platform that encompasses all of the steps in the modeling workflow — from defining geometries, material properties, and the physics that describe specific phenomena to solving and postprocessing models for producing accurate and. Where q is the frequency and dt is the time. Découvrez le profil de Paul Van Liedekerke sur LinkedIn, la plus grande communauté professionnelle au monde. meam => contains input parameters for the LAMMPS run Fe3C. The mean square displacement (MSD) of the center of mass of the fullerene in the two dimensional. The initial dose is 1014 cm–2. Thick b-SiC CVD-Coated SiC Die System for Dry Cold Forging of Metals. It will run on any parallel machine that compiles C++ and supports the MPI message-passing library. Complete Example for Self-Diffusion and Exponents from LAMMPS Includes readme. Example scripts. The jump size is J (μ J, σ J), with a normally distributed mean μ J, and a standard deviation σ J. Developed at Sandia National Laboratories by Dr. txt file; LAMMPS input file; FORTRAN source code for calculation of self-diffusivity; Excel file for checking and plotting; input file and code (zipped archive) Radial Distribution Function. For diamond structures, VSim for GaAs, Sb, and Diamond Semiconductor Devices models charge mobility, both hole and electron generation and transport. Relocation Diffusion example During colonial era, hundreds of thousands of Indians were transported to other contries including Africa, Carribean and South America, spreading Hinduism far beyond it's orginial core. The Visualization Toolkit (VTK) is open source software for manipulating and displaying scientific data. This includes time integration (update of coordinates and velocities), force constraints or boundary conditions (SHAKE or walls), and diagnostics (compute a diffusion coefficient). Most of the papers listed discuss simulation results generated with LAMMPS, but some describe other codes or algorithms and may only cite LAMMPS in passing. But, I'm not sure if it yields thermal conductivity in W/m-K units. The study of systems in. TITAN: Built for Science WL-LSMS Role of material disorder, statistics, and fluctuations in nanoscale materials and systems. LAMMPS is a classical molecular dynamics code, used to model atoms or, more generically, as a parallel particle simulator at the atomic, meso, or continuum scale, and runs on single processors or in parallel using message-passing techniques and a spatial-decomposition of the simulation domain. Maximum due to decreasing of diffusion constant. Examples: app_style potts/strain 100 See app_style diffusion for an Ising model which performs Kawasaki dynamics, meaning the spins on two neighboring sites The "couple" directory of the LAMMPS molecular dynamics package includes a sample coupled LAMMPS/SPPARKS application which uses LAMMPS to compute strain values at each site of a. LAMMPS Examples LAMMPS, or Large-scale Atomic/Molecular Massively Parallel Simulator, is a molecular dynamics simulator. of Materials Science & Engineering, University of Tennessee, Knoxville for example pressure gradient, a giving rise to a density. Evaluating Diffusion Coefficients in LAMMPS. zip contains an example equilibration for a UO 2 super-cell with the fluorite structure. Lecture 5: Diffusion Coefficient (Diffusivity) Today's topics • Understand the general physical meaning of diffusion coefficient. Getting Started; 3. 5 $$k_\mathrm{B} T$$. Materials Design, Inc. USim for High Energy Density Plasmas examples and documentation, demonstrating independent evolution of ions and electrons, coupling of ions, electron fluids, and electromagnetic fields, as well as general equation of state for ions and electrons, reduce your learning curve and ensure faster results. 33e−3 molecule/Å 3. This assumes that D i is a constant, which is only true for dilute solutions. COMSOL Multiphysics is a simulation platform that encompasses all of the steps in the modeling workflow — from defining geometries, material properties, and the physics that describe specific phenomena to solving and postprocessing models for producing accurate and. Thus, for each MD time step, we performed ten electronic heat conduction steps. ln lnγ} • { 1 + Understand the meaning of the. GREEN-KUBO RELATION To obtain transport coefﬁcients such as diffusion, viscosity,. 615 Å Construct 6 6 6 supercell cells , 864 atoms， lx ly lz 21. These tutorials and more may be seen on the Tech-X YouTube channels. I have also modified a number of these tutorials and updated with Python routines within Jupyter Notebooks, see my GitHub LAMMPS tutorial website. You should however not set this extremely high, as there is a chance that the simulation never will converge, for example if the problem is unsteady (vortex shedding etc). LAMMPS Molecular Dynamics Simulator. For this example, use the Mishin et al. gov) at Sandia and Todd Hoffmann (todd. Subject: [lammps-users] Reaxff simulation Dear All, I want to run a Reaxff simulation of water model from the following article: Second-Generation ReaxFF Water Force Field: Improvements in the Description of Water Density and OH-Anion Diffusion I have all the force field parameters. VII,wealso provide a comparison to the results of previous computer simulations [24,34,35]. OCTP is the first implementation in LAMMPS that uses the Einstein relations combined with the order-n. You can obtain LAMMPS and find the user manual here. The study of systems in. Examples of systems that can be modelled at the mesoscale include flows through complex geometries, microfluidics, solute diffusion, conductive and convective heat transfers, phase behaviours of fluids and polymers (e. aimed for gas separation have been proposed, for example functionalized porous graphene,32–35 multilayer carbon-based membranes,36–38 or nanoporous silica. Have you tried. Three salts comprised of LixNayKzCO3 near their respective eutectic concentrations are considered to understand the distribution of ions relative to a liquid-vacuum interface and their diffusivity. The vigorous motion of the intracellular fluid, known as cytoplasmic streaming, is caused by cytoskeletal filaments and molecular motors. Start a command shell, navigate to the gas folder (e. changed the layout of the remote job submission window. An example problem is. 08 kcal/mol vs 7. The EChemDID method includes a LAMMPS compute' that solves the Laplacian and a "fix" that integrates the voltage diffusion in time. An example is the link between the diffusion coefcient and velocity autocorrelation function (the former easy to measure experimentally, the latter Molecular dynamics simulation consists of the numerical, step-by-step, solution of the classical equations of motion, which for a simple atomic system may be written. lam to setup the simulation by executing lmp_serial -in gas. of Materials Science & Engineering, University of Tennessee, Knoxville for example pressure gradient, a giving rise to a density. Where q is the frequency and dt is the time. This includes time integration (update of coordinates and velocities), force constraints or boundary conditions (SHAKE or walls), and diagnostics (compute a diffusion coefficient). Consultez le profil complet sur LinkedIn et découvrez les relations de Paul, ainsi que des emplois dans des entreprises similaires. 6 nanoseconds but it. LAMMPS has potentials for soft materials (biomolecules, polymers) and solid-state materials (metals, semiconductors) and coarse-grained or mesoscopic systems. LAMMPS is a classical molecular dynamics code. There are many ways of describing diffusion in a biological system. Article describing spin-AM05: PRB 79, 155101 (2009). 608 × 10 −40 F·m 2. of Materials Science & Engineering, University of Tennessee, Knoxville for example pressure gradient, a giving rise to a density. 16 The library header files are installed in a subdirectory gsl of the main installation directory that must prefix preprocessing include statements, see e. out fix 2 all ttm 123456 1. By creating dislocations. This example will guide a new user through the process of setting up a simulation system containing a protein (lysozyme) in a box of water, with ions. Technology Skills & Tools Details Examples List Analytical or scientific software Examples relevant to your query "management software": 3D motion analysis software. Specifying the Thermodynamic State for example temperature, T, and pressure, p, or T and the number density, ρ. If the com option is set to yes then the effect of any drift in the center-of-mass of the group of atoms is subtracted out before the displacement of each atom is calculated. Using this protocol, the resulting diffusion coefficients were close to the ones obtained starting the workflow from PFF simulations, as shown on the right of Figure 6. **You can use octave (FREE) instead of MATLAB to run the script. Usage on Vilje. After the simulation is completed you can look at the JPEG pictures in the img folder or play the movie. Particle Diffusion To obtain equations of motion of selected particles that represent the biomolecules of interest for the signaling process studied, one may invoke the Mori-Zwanzig formalism. 9 In vesicle fusion during synaptic neurotransmission, the activity of SNARE proteins relies on spatial ordering of functional groups. New styles can be created to add new options to LAMMPS. The whole implementation is consistent with the parallel scheme employed in LAMMPS. Diffusion of water on carbon nanotubes (CNTs) 16. 1-3 weight percentage of nano graphene to EPON 862 polymer and an analytical model for moisture diffusion in presence of nano graphene was derived assuming time-dependent diffusivity and moisture boundary conditions. We found that two metastable conformations are present, with the triangle capable of assuming either an upward or downward concave shape with respect to the triangle surface normal. Getting Started; 3. This example will guide a new user through the process of setting up a simulation system containing a protein (lysozyme) in a box of water, with ions. 1995, 117, 1). 9 units (4-0-5); first, second, third terms. Multi-steps method for Navier-stokes equations with strongly nonlinear diffusion I am trying to solve a particular form of the Euler / Navier-Stokes equations in 1D, with very strong and non-linear diffusion coefficients. COMSOL Multiphysics is a simulation platform that encompasses all of the steps in the modeling workflow — from defining geometries, material properties, and the physics that describe specific phenomena to solving and postprocessing models for producing accurate and. At high concentration, there is a second peak observed at around 7 Å, likely present due to the high concentration in the bulk. Make the simulation box periodic in z via the boundary command. A C) and tracer diffusion coefficient (D. LAMMPS [15] molecular dynamics directly from BIOVIA Materials Studio. 1-3 weight percentage of nano graphene to EPON 862 polymer and an analytical model for moisture diffusion in presence of nano graphene was derived assuming time-dependent diffusivity and moisture boundary conditions. Examples of systems that can be modelled at the mesoscale include flows through complex geometries, microfluidics, solute diffusion, conductive and convective heat transfers, phase behaviours of fluids and polymers (e. 0 6 all npt. I'm interested in calculating the diffusion coefficient of self interstitial atom in iron system at 800 K. For example, this grain boundary set was first applied to the problem of dislocation nucleation in symmetric and asymmetric tilt grain boundaries [32, 33, 35], of which an example input script is included Footnote 6, but could easily be extended to any number of nanomechanical or materials science studies, atomistic or continuum in nature. LAMMPS (Large-scale Atomic/Molecular Massively Parallel Simulator) is a classical molecular dynamics simulation tool that is able to exploit modern parallel computing environments such as the cloud environments provided by Amazon and Microsoft. The library header files are installed in a subdirectory gsl of the main installation directory that must prefix preprocessing include statements, see e. There are many ways of describing diffusion in a biological system. Relaxation time, diffusion, and viscosity analysis of model asphalt systems using molecular simulation Liqun Zhanga and Michael L. Offered to B. The Materials Science and Engineering Department is the oldest and most diversified program in North Texas. Molecule Simulator. Diffusion Coefﬁcients were calculated for each molecule type using the mean-square displacement (MSD) of each molecule, also known as the Einstein Relation [13]. ACS Applied Materials & Interfaces 2018, 10 (42) , 36240-36248. diffusion coefficients in LAMMPS. An introduction on how to install and run a simple molecular dynamics simulation in LAMMPS. of ARMD in the popular LAMMPS molecular dynamics simulation package. Diffusion in Liquids from Molecular Dynamics Simulations. edu LAMMPS homepage: h. The corresponding formation energies are reported in the table below for a 3x3 MgO(100) surface. UT theoretical chemistry code forum. Where q is the frequency and dt is the time. As our second example, we took a one-dimensional diatomic chain, which is another typical example in many solid state physics textbooks ,. The resulting LAMMPS trajectory shows up on the LabFloor and can be visualized using the Movie Tool. These two possibilities are precisely what opens the division between the two processes. The LAMMPS distribution includes an examples sub-directory with several sample problems. out Description: Use a two-temperature model (TTM) to represent heat transfer through and between electronic and atomic subsystems. We will provide worked out examples using the kmos code, where we highlight the central approximations made in implementing a KMC model as well as possible pitfalls. SPPARKS Highlight (see the Pictures & Movies page for more examples of SPPARKS calculations). MDAnalysis is an object-oriented Python library to analyze trajectories from molecular dynamics (MD) simulations in many popular formats. LAMMPS is a classical molecular dynamics (MD) code widely used within the physics and materials science communities. It qualitatively shows that as n increases, the energy landscape felt by C 60 would possess separate deep potential wells which can trap C 60 and decrease its mobility. The Gibbs Open Source Thermodynamics Project and Integrated Computational Materials Engineering (ICME) Reactive Metals Workshop February 19, 2009. 0 3 all npt temp 300 100 0. The mean square displacement (MSD) of the center of mass of the fullerene in the two dimensional. Such reactions do not follow second order kinetics because at virtually every encounter of the acid and base, rapid proton transfer occurs and the reaction is complete. A combination of different models allowed us to determine the principal characteristics of self-diffusion along different types of GBs. Getting Started; 3. For the present example, use 3 layers for the substrate. For example, the cdo/2. The Pennsylvania State University This work shows that ion transport is accurately described by jump diffusion, which An example the Lennard Jones 12-6. Our implementation is built as an add-on to the Large-scale Atomic/Molecular Massively Parallel Simulator (LAMMPS) code. hoffmann at asu. For such systems, simulations must leave aside the full thermal description to focus specifically on mechanisms that generate a configurational change. The LAMMPS “version” is the date when it was released, such as 1 The LAMMPS. LAMMPS is run from the command line, reading commands from a file via the -in lmp_serial lammps/src/lmp_serial src # content files for LAMMPS documentation html # HTML version of the LAMMPS manual (see html/) tools # tools and settings for building the. The role of anomalous diffusion will be emphasized considering its physical relevance in many physical problems. Calculations were carried out for the {1 0 0}, {1 1 0} and {1 1 1} edge dislocations, the screw dislocation and Σ5, Σ13, Σ19 and Σ25 tilt grain boundaries. – Yesterday: Specific question about the diffusion of fission products. org。 请查阅 Debian 联系方式了解更多信息。. Such simulations are widely used in molecular dynamics (MD) to understand and predict properties of physical systems at the particle level. An example problem is. Steve Plimpton and his team, LAMMPS focuses on the efficient execution of computational tasks. html suffix of the URL you are browsing to. The LAMMPS distribution includes an examples sub-directory with several sample problems. ERIC Educational Resources Information Center. It includes potentials for solid-state materials (metals, semiconductors) and soft matter (biomolecules, polymers) and coarse-grained or mesoscopic systems. The discrete peri-dynamic model has the same computational structure as a molecular dynamics model. You certainly hear and read a lot about the advantages and benefits of the energy efficiency of LED light emitting diodes vs traditional lighting. We report that diffusion of Xe atoms in UO 2 fuel is important for nuclear fuel performance, and is enabled by interaction with U and O vacancies. An example of the complexity of the reaction mechanisms is shown in ﬁgure 5, where an annealing event. This is normally the original position at the time the compute command was issued, unless the average keyword is set to yes. An example protocol using this compo-nent has also been provided. LAMMPS A multiple capability molecular dynamics code. ch), Xuejin Li et al at the USI, Switzerland and Brown University, USA to develop new Open Boundary Condition (OBC) methods for particle-based methods suitable to simulate flow of deformable bodies in complex computational. Diffusion in Liquids from Molecular Dynamics Simulations. LAMMPS has potentials for soft materials (biomolecules, polymers) and solid-state materials (metals, semiconductors) and coarse-grained or mesoscopic systems. Modified from LAMMPS Examples Directory. A quick tutorial on how to use simple thermostats and model a diffusion process with the molecular dynamics code LAMMPS. LAMMPS Molecular Dynamics Simulator. , resulting. spera,1 an D Mark s. An introduction on how to install and run a simple molecular dynamics simulation in LAMMPS. bench benchmark problems couple code coupling examples using LAMMPS as a library doc documentation examples simple test problems lib libraries LAMMPS can be linked. In contrast, in solids, the. For example, Mahajan and. characteristics (LAMMPS) code [1. 3 are the density profiles of CO 2 in clay nanopores at two concentrations: 6. We present here the activation relaxation technique (ART), an open-ended saddle point search algorithm. Classical molecular dynamics simulation code (as. (a) Representative full-scale 3D calculation cell of the a-Li/c-Si diffusion couple used for the classical MD simulations. Generation and migration of helium and other point defects under irradiation causes ferritic steels based on the Fe-Cr system to age and fail. LAMMPS has potentials for solid-state materials (metals, semiconductors) and soft matter (biomolecules, polymers) and coarse-grained or mesoscopic systems. Fast diffusion of the encapsulated water is identified, with an anomalous temperarture dependence that indicates the solid-fluid nature of this structural transition. LAMMPS is a classical molecular dynamics code, used to model atoms or, more generically, as a parallel particle simulator at the atomic, meso, or continuum scale, and runs on single processors or in parallel using message-passing techniques and a spatial-decomposition of the simulation domain. LAMMPS and MedeA. Shodja's page. Thermal transport in graphene is a thriving area of research, thanks to graphene's extraordinary heat conductivity properties and its potential for use in thermal management applications. Thompson, Xiaowang Zhou, Jonathan A. performed using LAMMPS dynamical simulator, in particular the Einstein relation which links the diffusion coefﬁcient with the system temperature will be veriﬁed. Faculty in the Materials Science and Engineering doctoral program are committed to providing depth of understanding in their specialty, while recognizing the challenges facing students outside of their home science and engineering disciplines. Forcefield optimized for Ni/O, trained with a QM data on Ni, NiO and vacancies. 2 (from left to right) over a time Δ. New styles can be created to add new options to LAMMPS. David Keffer. Users are encouraged to download and use interatomic potentials, with proper acknowledgement, and developers are welcome to contribute potentials for inclusion. If the flame is not visible, the heavier-than-air propane gas may be escaping and could explode. Department of Materials Science & Engineering. Molecular Dynamics Simulation of Hard Spheres Simulate the motion of N colliding particles according to the laws of elastic collision using event-driven simulation. 16 The library header files are installed in a subdirectory gsl of the main installation directory that must prefix preprocessing include statements, see e. 1 modules lammps: 10Aug2015: lammps/10Aug2015: A diffusion-based imputation method reveals gene-gene interactions in single-cell RNA. Commands; 4. The dat file is in the lammps 'real' unit system and is can be directly read by lammps with the read_data ice-1c-40A-box. edu LAMMPS homepage: h. Unpack it with the following commands, and look for a README to get you started. Consultez le profil complet sur LinkedIn et découvrez les relations de Paul, ainsi que des emplois dans des entreprises similaires. Wavelengthλ WAVELENGTH, REFRACTIVE MICRONS INDEX 1. iCAST-ES 2019. However, this is not true for my actual data. LAMMPS is a classical molecular dynamics simulation code designed to run efficiently on parallel computers. diffusion coefficients in LAMMPS. The USER-MESO package appends new capabilities to LAMMPS for DPD simulations (beyond the classical DPD model). Mathematical diffusion modeling in social sciences is mostly based on an Ordinary Differential Equation-based (ODE) logistic function, which allows researchers to explore the rate of change of a variable over time. Other workers use diffuse electron density [] or polarizable versions of the non-polarizable models, using flexible bonding (for example, SWFLEX-AI), induced dipoles (for example, []), energy optimization (for example, the TIP4P-FQ version of TIP4P) or movable charge (for example, SWFLEX-AI), all of which generally give better. Sandia's molecular dynamics code LAMMPS now has its own download page. If the com option is set to yes then the effect of any drift in the center-of-mass of the group of atoms is subtracted out before the displacement of each atom is calculated. Using my program I calculated equilibrium state of N2 (as a point) The experimental self-diffusion coefficient is 14. in potential energy. It is a stand-alone code. The effects of collapse of the space charge field and of diffusion cooling are reviewed. Introduction; 2. LAMMPS input files This page makes various LAMMPS input files available for download. Changes in some commands may require revision of the input script. Case Study 3: Dynamical Properties: The Self-Diffusion Coefficient This Case Study combines elements of Case Studies 5 and 6 in F&S, which are unfortunately incomplete in their description. See below for a thorough description of how the model is specified to LAMMPS. I started with LAMMPS's example script which uses LJ units. viscosity, and the photoelectric effect. Wavelengthλ WAVELENGTH, REFRACTIVE MICRONS INDEX 1. One such surface that they tested was the hopping of Ag on Cu(111) using Large-scale Atomic/Molecular Massively Parallel Simulator (LAMMPS) [10]. Faculty of Science, Univ. For examples of LAMMPS simulations, see the Publications page of the LAMMPS WWW Site. •Fuel performance analysis code covering the full fuel life cycle and under accident scenarios. You can see from this simulation what the input files look like, and how to define your simulation cell and atomic coordinates. zip contains an example equilibration for a UO 2 super-cell with the fluorite structure. 15 m/s at 180 K Interface velocity divided by the average self diffusion constant. For the present example, use 3 layers for the substrate. This tutorial assumes you are using a GROMACS version in the 2018. The LAMMPS “version” is the date when it was released, such as 1 May 2010. For example, the computed diffusion constants for particles would give erroneous values. NRDF Radiation transport – important in astrophysics, laser fusion, combustion, atmospheric dynamics, and medical imaging – computed on AMR grids. , 6 tables, 25 figures, references, 34 titles. This problem is overcome by creating very long bonds in the polymerization stage, and then relaxing these to equilibrium values by using a directed‐diffusion‐based relaxation strategy. txt file; LAMMPS input file; FORTRAN source code for calculation of self-diffusivity; Excel file for checking and plotting; input file and code (zipped archive) Radial Distribution Function. 85 D from experiment), and α i is an isotropic polarizability constant, with a value of 1. Movies of water droplets on graphene. – Example: fast approximate methods to compute electrostatic interactions, or methods that allow you to evaluate some force field terms every other time step. Here, using state-of-the-art simulation methods, we show that treating the electronic degrees of freedom explicitly. The proportionality constant k is characteristic of the. Materials Design, Inc. ReaxFF-GUI tutorials¶ This section contains tutorials that show you how to use ReaxFF via the ReaxFF-GUI. Faculty in the Materials Science and Engineering doctoral program are committed to providing depth of understanding in their specialty, while recognizing the challenges facing students outside of their home science and engineering disciplines. For this example, use the Mishin et al. LAMMPS Tutorials. Just output one or more dump files and compute the MSD yourself at some time delta. The study of systems in. Example scripts. These tutorials and more may be seen on the Tech-X YouTube channels. Select the package you want via the circular check-button, click the "Download Now" button, and your browser should download a gzipped tar file. For example, the cdo/2. We describe a strategy for performing canonical and isothermal-isobaric ensemble hybrid Monte Carlo (HMC) simulations with the widely-used Large-scale Atomic/Molecular Massively Parallel Simulator (LAMMPS) molecular dynamics (MD) software package. Example 1-2: basics of TensorFlow and Deep Learning. Using my program I calculated equilibrium state of N2 (as a point) The experimental self-diffusion coefficient is 14. First, global connections, via trade, FDI [foreign direct investment], participation in GVCs [global value chains] and the international mobility of skilled labour. cpp is a simple example of setting forces on atoms to prescribed values. emphasis on colloid diffusion characteristics, and explore additional methodological details for all of these simula-tion techniques. We conclude this section, in 2. Usage on Vilje. The code presented here needs to work along with LAMMPS, an open-source molecular dynamics simulation package; it is designed as a user-contributed package to LAMMPS, thus making use of the features from LAMMPS. First-principles database used for MgY potential development. The effect of strain rate to the flow stress is mostly negligible near room temperature (e. LAMMPS input files This page makes various LAMMPS input files available for download. It includes potentials for solid-state materials (metals, semiconductors) and soft matter (biomolecules, polymers) and coarse-grained or mesoscopic systems. Mayank Agrawal, one of the current Ph. Predominantly vacancy in nature (difficult for atoms to “fit” into interstitial sites because of size. TEM images of high burn-up fuel pellets show that the dislocations are heavily decorated by ﬁssion product precipitates, including in the LAMMPS simulation package [33]. In this document, we examine. The glossary website page also lists MD terminology with links to corresponding LAMMPS manual pages. Michael Brown Prepared by Sandia National Laboratories Albuquerque, New Mexico 87185 and Livermore, California 94550. LAMMPS provides a tol value for each of the three-body entries so that they can be separately controlled. Tschopp, Email me Please contact me if you have any questions or comments about the tutorials. Relocation Diffusion example During colonial era, hundreds of thousands of Indians were transported to other contries including Africa, Carribean and South America, spreading Hinduism far beyond it's orginial core. A monocrystalline nanowire of Cu with a diameter of 3. Burton d and R. United States: N. LAMMPS has potentials for soft materials (biomolecules, polymers) and solid-state materials (metals, semiconductors) and coarse-grained or mesoscopic systems. • Reduce the number of time steps required to simulate a certain amount of physical time – One can increase the time step several fold by freezing out some very. The displacement of an atom is from its reference position. 0, then the standard Stillinger-Weber cutoff is used. Purdue e-Pubs is a service of the Purdue University Libraries, providing online publishing support for original publications as well as hosting for Purdue-affiliated articles, reports, conference proceedings, student scholarship, and more. Primary Knock-on from irradiation. Scope for diffusion depends on four key factors. The wave pulse is a product of Sin(2*PI*q*dt) and Cos(2*PI*q*dt) function. Stable vacancy structures; DOS; Attack frequency; Workfunction of hcp (0001) surfaces. To run the test, change directory to this folder and type make". Creating a High Entropy Alloy Atomic Mixture. Free diffusion models based on the Green's function of the diffusion equation and random walk algorithms have been used to describe diffusion of biomolecules over the length scale of organelles and entire cells, on the order of micrometers, while highly-detailed Brownian dynamics and molecular dynamics have been used in. aimed for gas separation have been proposed, for example functionalized porous graphene,32–35 multilayer carbon-based membranes,36–38 or nanoporous silica. At high temperatures, the. He carried out a classic experiment that you've probably done yourself in school: he set an alarm clock ringing, placed it inside a large glass jar, and while the clock was still ringing, sucked all the air out with a pump. ca website: Modeling and Simulation Research Group office: ICICS 175 Current Research Work I am interested in a number of problems related to the mechanics of materials, computational modelling. This includes the 5. The LAMMPS "version" is the date when it was released, such as 1 The LAMMPS documentation is organized into the following sections. In this case your reference system is either O 2 in the gas phase or a single oxygen atom. Download an input file. Shear viscosity and diffusion in liquid MgSiO 3: Transport properties and implications for terrestrial planet magma oceans Dean 1,nevins, * Frank J. lam to setup the simulation by executing lmp_serial -in gas. The role of anomalous diffusion will be emphasized considering its physical relevance in many physical problems. one or more keyword/value pairs may be. stuided the hetero-diffusion of metal atoms on other metal surfaces via adjacent hollow sites [9]. The partial differential equation for transient conduction heat transfer is:. The temperature of a bottom. In this case your reference system is either O 2 in the gas phase or a single oxygen atom. Ali Kerrache. USER-MESO package in LAMMPS:. [lammps-users] Diffusion Coefficient in 2D [lammps-users] Diffusion Coefficient in 2D. The notes begin with some formal theory and conclude with practical implementation. What I did was. A C = D A {1+ A A d. The rare event nature and the chemical bond breaking associated with these diffusions, however, make extensive simulations of these processes unpractical to ab initio and inappropriate for force field based methods. The implemented framework is based on a non-equilibrium statistical thermo-chemo-mechanical formulation of atomic systems where effective transport rates are computed by using kinematic diffusion laws. Getting Started; 3. In our group we look at lithium diffusion with atomistic potentials using NEB to get the activation barriers and MD to look at the diffusion. Just output one or more dump files and compute the MSD yourself at some time delta. If the diffusion model (Ratcliff & McKoon, 2008) is to account for the relative speeds of correct responses and errors, it is necessary that the components of processing identified by the model vary across the trials of a task. txt (not the same as viewing the source of the HTML file). characteristics (LAMMPS) code [1. This book serves two purposes: 1) to provide worked examples of using DFT to model materials properties, and 2) to provide references to more advanced treatments of these topics in the literature. The development of Gromacs would not have been possible without generous funding support from the BioExcel HPC Center of Excellence supported by the European Union Horizon 2020 Programme, the European Research Council, the Swedish Research Council, the Swedish Foundation for Strategic Research, the Swedish National Infrastructure for Computing, and the Swedish Foundation for International. while those are externally visible as separate entities, internally LAMMPS handles angles, bond-bond, and bond. Ali Kerrache. Wagner, Jie Deng, Lindsay C. Simulator (LAMMPS) program is being used for Molecular Dynamics simulation and the diffusion coefficients of the different species are determined from the slopes of the mean squared displacement (MSD) as a function of time. EON can use potentials from LAMMPS by linking EON to the LAMMPS library. A C) and tracer diffusion coefficient (D. 91 in pure EA is partially reverted to a conformation with ϕ = 2. Tracking the diffusion of an Cu atom sitting on top of a block of Cu with the (100) surface exposed. Initial coordinates are stored in "unwrapped" form, by using the image flags associated with each atom. 1 gives such examples of some physical quantities of interest in LJ units and in SI units (for the case in which the bead is the CH 2 unit of polyethylene or a possible group of polymer. Each step will contain an explanation of input and output, using typical settings for general use. COMSOL is a multiphysics simulation software with application areas in electrical, mechanical, fluids, acoustics and chemical. • Strain localization occurs in materials that have a high. mv${NAME} lammps_erase rm -rf lammps_erase & fi. This is motivation to study. Relaxation time, diffusion, and viscosity analysis of model asphalt systems using molecular simulation Liqun Zhanga and Michael L. It has a large user base across most areas of engineering and science, from both commercial and academic organisations. It comes with state-of-the-art tools for 3D rendering, a suite of widgets for 3D interaction, and extensive 2D plotting capability. Another example where atomistic simulations are useful is in studying gas/small molecule solubility/absorption/diffusion within pores of a polymer membrane, where the specific chemistry and size of the gas/small molecules impact its interactions with and solubilities in preassembled (glassy) polymers. 0A (command: neighbor 2. Howto discussions. 5 has a slope of 0. Courses; Courses. Subject: [lammps-users] Reaxff simulation Dear All, I want to run a Reaxff simulation of water model from the following article: Second-Generation ReaxFF Water Force Field: Improvements in the Description of Water Density and OH-Anion Diffusion I have all the force field parameters. MedeA ® Application Notes for Universities Molecular Dynamics Simulation of Crystalline C₆₀ Buckminsterfullerene with MedeA and LAMMPS This application note provides an overview of the forcefield based simulation of crystalline C₆₀ (Buckminsterfullerene) using the LAMMPS molecular dynamics simulation package. 0 4 all npt temp 300 100 0. I got a plot like (attached) this 'MSD vs time' using LAMMPS. Whether the surface is microscopically rough or smooth has a tremendous impact upon the subsequent reflection of a beam. •Fuel performance analysis code covering the full fuel life cycle and under accident scenarios. For example, the samples/PtIsland contains parameters for an akmc simulation of a Pt island diffusing. bench benchmark problems couple code coupling examples using LAMMPS as a library doc documentation examples simple test problems lib libraries LAMMPS can be linked. The program should run in a few seconds and report to stderr, a sub directory with the output will be created. 1, 2016, 2018, and 2019 release series. Another common use of QHA is to calculate the pre-factor for migration in a diffusion event. Many are 2d models that run quickly and are straightforward to visualize, requiring at most a couple of minutes to run on a desktop machine. in # Reference: Physical Chemistry Chemical Physics, 16(13) (2014):6233-6249. used the drag method. stl 5,120 × 2,880; 5. lam to setup the simulation by executing lmp_serial -in gas. I have also modified a number of these tutorials and updated with Python routines within Jupyter Notebooks, see my GitHub LAMMPS tutorial website. Multi-steps method for Navier-stokes equations with strongly nonlinear diffusion I am trying to solve a particular form of the Euler / Navier-Stokes equations in 1D, with very strong and non-linear diffusion coefficients. Simulation run using LAMMPS with modified in. [lammps-users] Diffusion Coefficient in 2D [lammps-users] Diffusion Coefficient in 2D. LAMMPS gives dihedral_style, as an option. Click on whichever potential you like. while those are externally visible as separate entities, internally LAMMPS handles angles, bond-bond, and bond. Keffer, MSE 614, Dept. Advances in computing has fundamentally altered how such networks can be synthesized, analyzed and reasoned. For example, we can use % numSpecies 1 648 1296 % EndNumSpecies % speciesSymbol CH4 Si O % EndSpeciesSymbol. The LAMMPS “version” is the date when it was released, such as 1 May 2010. : \$ module load intelcomp/13. Einstein's contributions were 1. Lecture 26: Diffusion of Ions: Part 1: basic understanding and the derivation of diffusion flux. The displacement of an atom is from its original position at the time the compute command was issued. For each force call, EON updates the positions of the atoms in LAMMPS and calls the application programming interface (API) to update the. 3DPX-003145 Fractional Anisotrpy Tractography White Matter NevitDilmen. Example 3-5: Training and MD. Thompson, Xiaowang Zhou, Jonathan A. An approach for computing Fick diffusivities directly from equilibrium molecular dynamics (MD) simulations is presented and demonstrated for a ternary chloroform–acetone–methanol liquid mixture. From advanced control systems in modern aircrafts to pacemakers, computers, mobile phones, digital cameras, and control panels on our appliances, we count on electronics to improve the quality and efficiency of our lives.
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Canadian Mathematical Society www.cms.math.ca
 location:  Publications → journals → CMB
Abstract view

On Frankel's Theorem

Published:2003-03-01
Printed: Mar 2003
• Peter Petersen
• Frederick Wilhelm
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Abstract

In this paper we show that two minimal hypersurfaces in a manifold with positive Ricci curvature must intersect. This is then generalized to show that in manifolds with positive Ricci curvature in the integral sense two minimal hypersurfaces must be close to each other. We also show what happens if a manifold with nonnegative Ricci curvature admits two nonintersecting minimal hypersurfaces.
 Keywords: Frankel's Theorem Frankel's Theorem
 MSC Classifications: 53C20 - Global Riemannian geometry, including pinching [See also 31C12, 58B20]

© Canadian Mathematical Society, 2014 : http://www.cms.math.ca/

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• ### Parton Radiation and Fragmentation from LHC to FCC-ee(1702.01329)

Feb. 4, 2017 hep-ph, hep-ex
This document collects the proceedings of the "Parton Radiation and Fragmentation from LHC to FCC-ee" workshop (http://indico.cern.ch/e/ee\_jets16) held at CERN in Nov. 2016. The writeup reviews the latest theoretical and experimental developments on parton radiation and parton-hadron fragmentation studies --including analyses of LEP, B-factories, and LHC data-- with a focus on the future perspectives reacheable in $e^+e^-$ measurements at the Future Circular Collider (FCC-ee), with multi-ab$^{-1}$ integrated luminosities yielding 10$^{12}$ and 10$^{8}$ jets from Z and W bosons decays as well as 10$^5$ gluon jets from Higgs boson decays. The main topics discussed are: (i) parton radiation and parton-to-hadron fragmentation functions (splitting functions at NNLO, small-$z$ NNLL resummations, global FF fits including Monte Carlo (MC) and neural-network analyses of the latest Belle/BaBar high-precision data, parton shower MC generators), (ii) jet properties (quark-gluon discrimination, $e^+e^-$ event shapes and multi-jet rates at NNLO+N$^{n}$LL, jet broadening and angularities, jet substructure at small-radius, jet charge determination, $e^+e^-$ jet reconstruction algorithms), (iii) heavy-quark jets (dead cone effect, charm-bottom separation, gluon-to-$b\bar{b}$ splitting), and (iv) non-perturbative QCD phenomena (colour reconnection, baryon and strangeness production, Bose-Einstein and Fermi-Dirac final-state correlations, colour string dynamics: spin effects, helix hadronization).
• ### High-precision $\alpha_s$ measurements from LHC to FCC-ee(1512.05194)

Dec. 16, 2015 hep-ph, hep-ex
This document provides a writeup of all contributions to the workshop on "High precision measurements of $\alpha_s$: From LHC to FCC-ee" held at CERN, Oct. 12--13, 2015. The workshop explored in depth the latest developments on the determination of the QCD coupling $\alpha_s$ from 15 methods where high precision measurements are (or will be) available. Those include low-energy observables: (i) lattice QCD, (ii) pion decay factor, (iii) quarkonia and (iv) $\tau$ decays, (v) soft parton-to-hadron fragmentation functions, as well as high-energy observables: (vi) global fits of parton distribution functions, (vii) hard parton-to-hadron fragmentation functions, (viii) jets in $e^\pm$p DIS and $\gamma$-p photoproduction, (ix) photon structure function in $\gamma$-$\gamma$, (x) event shapes and (xi) jet cross sections in $e^+e^-$ collisions, (xii) W boson and (xiii) Z boson decays, and (xiv) jets and (xv) top-quark cross sections in proton-(anti)proton collisions. The current status of the theoretical and experimental uncertainties associated to each extraction method, the improvements expected from LHC data in the coming years, and future perspectives achievable in $e^+e^-$ collisions at the Future Circular Collider (FCC-ee) with $\cal{O}$(1--100 ab$^{-1}$) integrated luminosities yielding 10$^{12}$ Z bosons and jets, and 10$^{8}$ W bosons and $\tau$ leptons, are thoroughly reviewed. The current uncertainty of the (preliminary) 2015 strong coupling world-average value, $\alpha_s(m_Z)$ = 0.1177 $\pm$ 0.0013, is about 1\%. Some participants believed this may be reduced by a factor of three in the near future by including novel high-precision observables, although this opinion was not universally shared. At the FCC-ee facility, a factor of ten reduction in the $\alpha_s$ uncertainty should be possible, mostly thanks to the huge Z and W data samples available.
• ### Medium-modified DGLAP evolution of fragmentation functions from large to small x(0903.4825)

May 14, 2009 hep-ph
The unified description of fragmentation function evolution from large to small x which was developed for the vacuum in previous publications is now generalized to the medium, and is studied for the case in which the complete contribution from the largest class of soft gluon logarithms, the double logarithms, are accounted for and with the fixed order part calculated to leading order. In this approach it proves possible to choose the remaining degrees of freedom related to the medium such that the distribution of produced hadrons is suppressed at large momenta while the production of soft radiation-induced charged hadrons at small momenta is enhanced, in agreement with experiment. Just as for the vacuum, our approach does not require further assumptions concerning fragmentation and is more complete than previous computations of evolution in the medium.
• ### Parton fragmentation in the vacuum and in the medium(0804.2021)

April 12, 2008 hep-ph
We present the mini-proceedings of the workshop on Parton fragmentation in the vacuum and in the medium'' held at the European Centre for Theoretical Studies in Nuclear Physics and Related Areas (ECT*, Trento) in February 2008. The workshop gathered both theorists and experimentalists to discuss the current status of investigations of quark and gluon fragmentation into hadrons at different accelerator facilities (LEP, B-factories, JLab, HERA, RHIC, and Tevatron) as well as preparations for extension of these studies at the LHC. The main physics topics covered were: (i) light-quark and gluon fragmentation in the vacuum including theoretical (global fits analyses and MLLA) and experimental (data from e+e-, p-p, e-p collisions) aspects, (ii) strange and heavy-quark fragmentation, (iii) parton fragmentation in cold QCD matter (nuclear DIS), and (iv) medium-modified fragmentation in hot and dense QCD matter (high-energy nucleus-nucleus collisions). These mini-proceedings consist of an introduction and short summaries of the talks presented at the meeting.


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• # question_answer Two spheres of radii ${{R}_{1}}$ and ${{R}_{2}}$ respectively are charged and joined by a wire. The ratio of electric field of sphere will be: A)  $\frac{2R_{2}^{2}}{R_{1}^{2}}$                    B)  $\frac{R_{1}^{2}}{R_{2}^{2}}$C)  $\frac{{{R}_{2}}}{{{R}_{1}}}$                          D)  $\frac{{{R}_{1}}}{{{R}_{2}}}$

It is quite clear, when the two spheres joined by a wire the charge will redistribute and will stop if the potential become equal i.e. ${{V}_{1}}={{V}_{2}}$ When ${{q}_{1}}$ and ${{q}_{2}}$ are charge after redistribution then             $\frac{{{q}_{1}}}{4\pi {{\varepsilon }_{0}}{{R}_{1}}}=\frac{{{q}_{2}}}{4\pi {{\varepsilon }_{0}}{{R}_{2}}}$             $\frac{{{q}_{1}}}{{{q}_{2}}}=\frac{{{R}_{1}}}{{{R}_{2}}}$ Again,       $\frac{{{\varepsilon }_{1}}}{{{\varepsilon }_{2}}}=\frac{{{q}_{1}}}{4\pi {{\varepsilon }_{0}}R_{1}^{2}}\times \frac{4\pi {{\varepsilon }_{0}}R_{2}^{2}}{{{q}_{2}}}$ $\Rightarrow$            $\frac{{{\varepsilon }_{1}}}{{{\varepsilon }_{2}}}=\frac{{{q}_{1}}}{{{q}_{2}}}\times \frac{R_{2}^{2}}{R_{1}^{2}}$ $\Rightarrow$            $\frac{{{\varepsilon }_{1}}}{{{\varepsilon }_{2}}}=\frac{{{R}_{1}}}{{{R}_{2}}}\times \frac{R_{2}^{2}}{R_{1}^{2}}$ $\Rightarrow$            $\frac{{{\varepsilon }_{1}}}{{{\varepsilon }_{2}}}=\frac{{{R}_{1}}}{{{R}_{2}}}$


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Free Version
Moderate

# The Wall Separating the Lateral Ventricles

NEURO-6GDN@D

In the brain, there is a wall separating the two lateral ventricles.

What is the wall between the two lateral ventricles called?

A

Septum pullicidum.

B

Hippocampus.

C

Globus pallidus.

D

Cerebral ganglia.

E

Temporal lobe.


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Weighted average cost of capital (WACC) is used by analysts and investors to assess an investor's returns on an investment in a company. As the majority of businesses run on borrowed funds, the cost of capital becomes an important parameter in assessing a firm’s potential for net profitability. WACC measures a company’s cost to borrow money, where the WACC formula uses both the company’s debt and equity in its calculation.

### Key Takeaways

• The weighted average cost of capital (WACC) is a calculation of a firm's cost of capital in which each category of capital is proportionately weighted.
• All sources of capital, including common stock, preferred stock, bonds, and any other long-term debt, are included in a WACC calculation.
• WACC is calculated by multiplying the cost of each capital source (debt and equity) by its relevant weight by market value, and then adding the products together to determine the total.
• The cost of equity can be found using the capital asset pricing model (CAPM).
• WACC is used by investors to determine whether an investment is worthwhile, while company management tends to use WACC when determining whether a project is worth pursuing.
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## What Is the Weighted Average Cost of Capital (WACC)?

WACC is the average after-tax cost of a company’s various capital sources, including common stock, preferred stock, bonds, and any other long-term debt. In other words, WACC is the average rate a company expects to pay to finance its assets.

Companies often run their business using the capital they raise through various sources. They include raising money through listing their shares on the stock exchange (equity), or by issuing interest-paying bonds or taking commercial loans (debt). All such capital comes at a cost, and the cost associated with each type varies for each source.

Since a company’s financing is largely classified into two typesdebt and equityWACC is the average cost of raising that money, which is calculated in proportion to each of the sources.

### Why the WACC Formula Is Important

WACC is a formula that gives insight into how much interest a company owes for each dollar it finances. Analysts use WACC to assess the value of an investment. WACC is a key number used in discounted cash flow (DCF) analysis. Company management also uses WACC figures as a hurdle rate when choosing which projects to undertake. Meanwhile, investors will use WACC when assessing whether an investment is viable.

## The Formula for WACC

The WACC formula includes the weighted average cost of equity plus the weighted average cost of debt. Note that, generally, the cost of debt is lower than the cost of equity given that interest expenses are tax-deductible.

\begin{aligned} &\text{WACC} = \left ( \frac{ E }{ V} \times Re \right ) + \left ( \frac{ D }{ V} \times Rd \times ( 1 - Tc ) \right ) \\ &\textbf{where:} \\ &E = \text{Market value of the firm's equity} \\ &D = \text{Market value of the firm's debt} \\ &V = E + D \\ &Re = \text{Cost of equity} \\ &Rd = \text{Cost of debt} \\ &Tc = \text{Corporate tax rate} \\ \end{aligned}

## How to Calculate WACC

WACC formula is the summation of two terms:

$\left ( \frac{ E }{ V} \times Re \right )$
$\left ( \frac{ D }{ V} \times Rd \times ( 1 - Tc ) \right )$

The former represents the weighted value of equity-linked capital, while the latter represents the weighted value of debt-linked capital.

The calculation of the WACC generally uses the market value of the various components versus book value—because the expected cost of new capital is more important than the sale of existing assets for WACC purposes.

### Equity and Debt Components of WACC Formula

WACC is calculated by multiplying the cost of each capital source (debt and equity) by its relevant weight, and then adding the products together to determine the value. In the above formula, E/V represents the proportion of equity-based financing, while D/V represents the proportion of debt-based financing.

It's a common misconception that equity capital has no concrete cost that the company must pay after it has listed its shares on the exchange. In reality, there is a cost of equity. The shareholders' expected rate of return is considered a cost from the company's perspective.

That's because if the company fails to deliver this expected return, shareholders will simply sell off their shares, which will lead to a decrease in share price and the company’s overall valuation. The cost of equity is essentially the amount that a company must spend in order to maintain a share price that will keep its investors satisfied and invested.

One can use the CAPM (capital asset pricing model) to determine the cost of equity. CAPM is a model that established the relationship between the risk and expected return for assets and is widely followed for the pricing of risky securities like equity, generating expected returns for assets given the associated risk, and calculating costs of capital.

The CAPM requires the risk-free rate, beta, and historical market return—note that the equity risk premium (ERP) is the difference between the historical market return and the risk-free rate.

Generally, the lower the WACC the better. A lower WACC represents lower risk for a company's operations.

The debt portion of the WACC formula represents the cost of capital for company-issued debt. It accounts for interest a company pays on the issued bonds or commercial loans taken from the bank.

## Example of How to Use WACC

Let's calculate the WACC for retail giant Walmart (WMT). In April 2021, the risk-free rate as represented by the annual return on a 20-year treasury bond was 2.21%. Walmart's beta was 0.48 as of April 14, 2021. Meanwhile, the average long-term return of the market is roughly 8%. Using the CAPM, Walmart's cost of equity is 4.99%.

The market cap for Walmart was $394 billion as of April 14, 2021. The long term debt stood at$44 billion as of the end of fiscal year 2021 and its average cost of debt was 3.9%.

The WACC for Walmart is as follows:

V = E + D = $394 billion +$44 billion = \$438 billion

The equity-linked cost of capital for Walmart is:

(E/V) x Re = (394 / 438) x 4.99% = 0.045

The debt component is:

(D/V) x Rd x (1 - Tc) = (44 / 438) x 3.9% x (1 - 33.3%) = 0.0026

Using the above two computed figures, WACC for Walmart can be calculated as:

0.045 + 0.0026 = 4.76%

On average, Walmart is paying around 4.76% per year as the cost of overall capital raised via a combination of debt and equity.

The above example is a simple illustration to calculate WACC. One may need to compute it in a more elaborate manner if the company is having multiple forms of capital with each having a different cost.

For instance, if the preferred shares are trading at a different price than common shares, if the company issued bonds of varying maturity are offering different returns, or if the company has a commercial loan at different interest rates, then each such component needs to be accounted for separately and added together in proportion of the capital raised.

There are online calculators that can be used to calculate WACC.

## Limitations of WACC

The WACC can be difficult to calculate if you're not familiar with all the inputs. Higher debt levels mean the investor or company will require higher WACCs. More complex balance sheets, such as varying types of debt with various interest rates, make it more difficult to calculate WACC. There are many inputs to calculating WACC—such as interest rates and tax rates—all of which can be affected by market and economic conditions.

Together, the debt and equity mix of a company are considered its capital structure. One downside to the WACC is that it assumes a set capital structure. That is, the WACC assumes that the current capital structure will remain the same in the future.

Another limitation of WACC is the fact that there are various ways of calculating the formula, which can leave to different results. The WACC is also not suitable for accessing risky projects because to reflect the higher risk the cost of capital will be higher. Instead, investors may opt to use the adjusted present value (APV), which does not use the WACC.

## WACC FAQs

### What Is the WACC Formula?

The WACC formula is calculated as (E/V * Re) + [D/V * Rd * (1 - Tc)].

### How Do I Calculate WACC?

WACC is calculated with the following variables: E is the firm's equity market value, D is the firm's debt market value, Re is the cost of equity, Rd is the cost of debt, and Tc is the corporate tax rate.

### What Is a Good WACC?

A “good” WACC is usually a lower WACC. A high WACC is generally a signal of higher risk. All else equal, the lower the WACC the higher the market value of the company.

### What Is the WACC Used For?

WACC is used as a benchmark on whether to invest in a project or company. It’s an internal calculation to determine a company’s cost of capital.

### Is WACC Nominal or Real?

WACC is based on nominal rates, and thus, most WACC calculations are considered nominal. The inputs for the WACC calculation are nominal, such as the cost of debt, bond cash flows, stock prices, and free cash flows.

## The Bottom Line

WACC is a formula that takes into account a company's cost debt and equity using a formula, although it can also be calculated using excel. The formula is useful analysts, investors, and company management—all of whom use it for different purposes.


text:
task co to jest
ABAP definicja task (EC-CS). Co znaczy system from an accounting perspective. You can define tasks.

Czy przydatne?

# Definicja task (EC-CS)

Co znaczy:

Consolidation step in the system from an accounting perspective.

You can define tasks for the the various steps to reflect your business activities.

Example:

Within your statutory dimension of consolidation, you can define that interunit elimination is achieved with the tasks for the elimination of IU payables and receivables, the elimination of IU revenue and expense, and the elimination of investment income.

Słownik i definicje SAPa na .


text:
# ABCD is a rectangle, the coordinates of two vertices A and C are (2,3) and (7,7) , find the cordinatesof remaining vertices .

• 9
(2,7) (7,3)
• -3
What are you looking for?


text:
## Stat. mech. says: temperature ALWAYS infinite; what goes wrong?

So let's be clear: the result of the following calculation is non-sensical. What I'm trying to figure out is: what step is making it non-sensical.

I'm working in a microcanonical ensemble with energy E. The corresponding phase volume is $|\Omega| = \int \delta(E- \mathcal H(X)) \mathrm d X$ (H is the Hamiltonian of course, X a microstate) and the entropy is $S = k_B \ln |\Omega|$.

Now, (inverse) temperature is $\beta = \frac{\partial S}{\partial E} = \frac{k_B}{|\Omega|} \cdot \frac{\partial}{\partial E} \int \delta(E- \mathcal H(X)) \mathrm d X$.

Assuming I can bring the derivative inside (we always do in physics...), we get

$\beta \propto \int \delta'(E- \mathcal H(X)) \mathrm d X$

But this is zero!

If this last step is not immediately clear, note that $\int f(x) \delta'(g(x)-a) \mathrm d x = - \int f'(x) \delta(g(x)-a) \mathrm d x$ due to partiel integration (explained in e.g. Griffiths' Introduction to Electrodynamics)

EDIT: an easier way to see the delta-derivative integral is zero: the derivative of an even function (delta function!) is odd.
 PhysOrg.com physics news on PhysOrg.com >> A quantum simulator for magnetic materials>> Atomic-scale investigations solve key puzzle of LED efficiency>> Error sought & found: State-of-the-art measurement technique optimised
 I can't tell for sure since I don't know much about this branch of physics, but it seems it might be related to the "any warm body emits infinite radiation" problem, which was solved by QM?
 No the result itself is wrong, I just need to find out where in the computation it went wrong.

Recognitions:
Gold Member
Homework Help

## Stat. mech. says: temperature ALWAYS infinite; what goes wrong?

The measure ##dX## over the microstates is not independent of the energy. Not only is the term that you write down not zero in general, but there will be an additional term where the energy derivative acts on the measure. You can see how it works for a gas of free particles if you look over the computations at http://www.nyu.edu/classes/tuckerman...e_6/node2.html.
 I'm pretty sure dX cannot depend on E... It seems like that statement doesn't make a lot of sense. What do you even mean by it? But can you help me out in this specific example: Take a 1D harmonic oscillator with a 2D phase space. The Hamiltonian is $\mathcal H(X) = x^2 + p^2$. Hence $|\Omega| = \iint \delta(x^2+p^2-E) \mathrm d x \mathrm d p$. We can calculate it explicitly: $|\Omega| = 2 \pi \int \delta(r^2-E) \cdot r \cdot \mathrm dr = \pi \int \delta(r^2- E) \mathrm d( r^2) = \pi$ No E-dependence...

Recognitions:
Gold Member
Homework Help
 Quote by mr. vodka I'm pretty sure dX cannot depend on E... It seems like that statement doesn't make a lot of sense. What do you even mean by it? But can you help me out in this specific example: Take a 1D harmonic oscillator with a 2D phase space. The Hamiltonian is $\mathcal H(X) = x^2 + p^2$. Hence $|\Omega| = \iint \delta(x^2+p^2-E) \mathrm d x \mathrm d p$. We can calculate it explicitly: $|\Omega| = 2 \pi \int \delta(r^2-E) \cdot r \cdot \mathrm dr = \pi \int \delta(r^2- E) \mathrm d( r^2) = \pi$ No E-dependence...
You are right, in the classical case, the measure is not explicitly a function of the energy. However, we can see the problem, since a single harmonic oscillator is not an ensemble. Consider ##N## of them, subject to the condition

$$\sum_{i=1}^N \left( p_i^2 + x_i^2 \right) = 2 E.$$

Then the phase space is a ##2N##-dimensional sphere with volume

$$\Omega = \frac{\pi^N}{N!} \int \delta(R^2-2E) R^{2N-1} dR \sim \frac{(2\pi)^N}{N!}E^{N-1}.$$

Note that the entire concept of temperature relies on the notion of having a large number of microscopic systems in near thermal equilibrium. We cannot define the temperature of a single particle.
 Yes, I agree the physics only makes sense for an ensemble, I simply hadn't expected that whether or not it would depend on E (at all) would depend on dimensionality, but I see I was wrong! My example was misleading since $E^{1-1} = 1$. Thank you for clearing that up! And I also believe I understand what you mean about my original claim that that certain integral was zero. It seems it doesn't need to be: do you agree that if we have an n-dimensional phase space then $\int \delta'(E- \mathcal H(X)) \mathrm d X = - \int \frac{\partial}{\partial H} \delta(E-H) \cdot H^{(n-1)/2} \cdot \mathrm d H \mathrm d^{n-1} (\cdots)$ where I've done a change in coordinates and one of the new coordinates is H which is equal in value to the Hamiltonian in a certain point (i.e. the new coordinate system labels each energy shell; the other coordinates aren't written down explicitly as they are not important for what follows) Partial integration: $= \int \delta(E-H) \cdot \frac{n-1}{2} H^{(n-3)/2} \cdot \mathrm d H \mathrm d^{n-1} (\cdots) = \frac{n-1}{2E} \int \delta(E-\mathcal H(X)) \mathrm d X$ Hmmm... wait this should give zero for n = 2 (as we just cleared up) Also this calculation is probably only valid for special kinds of Hamiltonians? Namely ones where there are only quadratic terms in phase space variables?
 Recognitions: Gold Member Homework Help Science Advisor If the Hamiltonian was not quadratic, the constant energy surface will not be a sphere. For a more complicated Hamiltonian, it's might be easier to compute the phase space volume ##V(E)## for all states satisfying ##\mathcal{H}\leq E##. Then you can compute the volume of the piece with energies between ##E## and ##E+dE## from ##\Omega(E) = dV(E)/dE##. This bypasses whatever funny dependence the argument of the delta function has, but the total volume integral might not be much easier to do.
 But say I'm not specifically interested in calculating the volume, but in doing a calculation as shown in my previous post. Are there then constraints on my Hamiltonian? Note that that calculation is equivalent with $\beta = \frac{n-1}{2E}$ with n the dimension of phase space (although I feel I must've made a minor mistake somewhere since it doesn't give the right answer for my harmonic oscillator example) Thank you for your time by the way.

Recognitions:
Gold Member
Homework Help
 Quote by mr. vodka But say I'm not specifically interested in calculating the volume, but in doing a calculation as shown in my previous post. Are there then constraints on my Hamiltonian? Note that that calculation is equivalent with $\beta = \frac{n-1}{2E}$ with n the dimension of phase space (although I feel I must've made a minor mistake somewhere since it doesn't give the right answer for my harmonic oscillator example).


text:
Medians of Triangle

In a triangle, a median is a line joining a vertex with the mid-point of the opposite side.
Every triangle have 3 medians.

The three medians meet at one point called centroid - point G.

Here the medians are AX, BY, CZ and they meet at G.

The G point separates each into segments in ratio 2 : 1 i.e.:

$\frac{\overline{AG}}{\overline{GX}} = \frac{\overline{BG}}{\overline{GY}} = \frac{\overline{CG}}{\overline{GZ}} = \frac21$

and

$\frac{\overline{AG}}{\overline{AX}} = \frac{\overline{BG}}{\overline{BY}} = \frac{\overline{CG}}{\overline{CZ}} = \frac23$

and

$\frac{\overline{GX}}{\overline{AX}} = \frac{\overline{GY}}{\overline{BY}} = \frac{\overline{GZ}}{\overline{CZ}} = \frac13$

Median length formulas

Let's denote the medians by ma, mb, mc and the triangle sides by a, b, c.

$m_a = \frac{1}{2}\sqrt{2c^2+2b^2-a^2}$

$m_b = \frac{1}{2}\sqrt{2c^2+2a^2-b^2}$

$m_c = \frac{1}{2}\sqrt{2a^2+2b^2-c^2}$

Here are the formulas for calculating sides of a triangle when we have medians lengths.

$a = \frac{2}{3}\sqrt{2m_b^2+2m_c^2-m_a^2}$

$b = \frac{2}{3}\sqrt{2m_c^2+2m_a^2-m_b^2}$

$c = \frac{2}{3}\sqrt{2m_a^2+2m_b^2-m_c^2}$

Contact email:


text:
# Battery Chargers DOA Model HF #45005

#### Woodman

Dec 3, 2012
47
Hello gang!

Recently I purchased two 6/12 volt battery chargers with 2 and 6 amp modes at EBAY. A liquidator was ditching for Harbor Freight, made by Chicago Electric. Retail is $60 for both and I paid$19 for both including shipping knowing that both were not working. Thought I could get at least one if not both going and now am having some problems. Manual states they don't sell replaceable parts, and I have at least one bad part. The diode in the bottom right corner of first BAT charger (see pic of circuit board) gets very hot when plugged into mains for a few seconds with battery attached. The board has two diodes labeled scr1 and scr2, and they are stamped as BT151 25J TRANSUN. Ebay sells similar SCRs for \$4 including shipping. I suppose I could swap good diode from other charger but that one works fine.
The second charger was also DOA originally. Noticed that there was no continuity on one of the primary leads so I moved to a different lead and now secondary output tests ok so one charger appears to be working already.

Woody

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#### Woodman

Dec 3, 2012
47
mystery component

Just thought of another question. If I peel back a layer of tape wrap on the primary there is a mysterious little rectangle box like device that I can't ID. The photo is a little shaded but on the top of this thing on either side there are two wires coming out of it. One attaches to the first of five primary leads and the other attaches to the last lead. As far as I can tell it just links both leads electronically. But there is no continuity between first and fifth lead. Also the first lead has no continuity between any of the other leads. What is this item?

Both chargers were DOA, so to power them, I shifted the AC black mains live lead (moved live ac wire from 1st to 5th lead). The only thing I can think of, is that the wire has a bad connection to 1st lead on both battery chargers. This liquidator is selling these things by the truckload so I think there is definitely some quality control issues going on with these units. Most are being resold as working units, but a ton of them have also sold in pairs of two as not working.

Woody

UPDATE: As Dave explains below, this unkown item is a fuse between lead 1 and 5 that blew on both my chargers. If yours blew, the fuse should be replaced as it protects the transformer. I did not know there were any marking on it but when I clipped it off markings became visable with a mag.glass. It is rated at 2amps 240 volts and blows @ 130 centigrade.

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#### davenn

Moderator
Sep 5, 2009
14,150
Just thought of another question. If I peel back a layer of tape wrap on the primary there is a mysterious little rectangle box like device that I can't ID. The photo is a little shaded but on the top of this thing on either side there are two wires coming out of it. One attaches to the first of five primary leads and the other attaches to the last lead. As far as I can tell it just links both leads electronically. But there is no continuity between first and fifth lead. Also the first lead has no continuity between any of the other leads. What is this item?

Woody

welcome to the forums

its a thermal fuse if its open circuit, then there will be no current flowing through the primary

Dave

#### Woodman

Dec 3, 2012
47
welcome to the forums

its a thermal fuse if its open circuit, then there will be no current flowing through the primary

Dave

Dave, thanks for the welcome -great site you Aussies have here!

Since my primary taps are open between taps 1 and 5 then I assume fuses on both chargers blew. I have several spare regular fuses on hand ranging from .2 to 30 amp -can I use one of these fuses to replace and what size would you recommend?

Cheers,
Woody

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#### (*steve*)

##### ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd
Moderator
Jan 21, 2010
25,508
Dave, thanks for the welcome -great site you Aussies have here!

I'm sure the Australian moderators would love to take credit for this entire site, however this site is here thanks to Ian (who's British) and we have another moderator who is also German.

You may have just visited us while us Aussies were awake and active

#### Jotto

Aug 24, 2012
120
Regarding the first BAT charger that is not working, do you think that replacing the pair of SCRs would be a good idea and if so what diodes would you replace with? Any other recommendations would be greatly appreciated.

Cheers,
Woody

You can test the SCR's with a meter. If they are high voltage ones they won't stay shorted, but low voltage ones will.

#### Woodman

Dec 3, 2012
47
Quality Control @ Chicago Electric

UPDATE...

I removed the board to examine with a glass, and noticed that two different, smaller power diodes were accidentally soldered together. A brief hot touch with hot solder wick remedied that problem. Now when I plug AC cord in, there is no smoking hot diode, and there are normal secondary transformer readings. HOWEVER, when I add/connect it to a live battery then the same large diode is still smoking hot.

Woody

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#### Woodman

Dec 3, 2012
47
Before I order some diodes that may or may not even work, I remembered a "small" detail that I definitely should have mentioned. The attached pics show that the transformer on the non working BAT charger may have some shorted windings. Notice how the yellow wrapping around the primary windings looks like they may have melted a little.

As previously stated, when I plug charger into mains, the secondary voltages are all good, but when a car battery is connected to DC output then that larger diode still gets very hot. The transformer does not get hot with just AC connected, and does not get hot with BAT added -though I only connected battery for a few seconds. Could this transformer be toast, and how do I test to see if it's toast?

Woody

PS for some reason could not post 2 pics and will try at another time, but wrap looks to be partially melted.

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#### Woodman

Dec 3, 2012
47
melted plastic wrap pics attached -toasted or ready-to-be toasted transformer?

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#### Woodman

Dec 3, 2012
47
Unidentified cracking sound ?

melted plastic wrap pics attached -toasted?

Not sure if I mentioned this fact or not -- as per manual instructions, I hook mains AC first to charger then DC clips to battery. Now on mine, I always turn it off after a few seconds after battery connected because there is a loud cracking sound every time. Do you think that cracking sound is coming from the transformer or the hot diode?

Woody

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#### (*steve*)

##### ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd
Moderator
Jan 21, 2010
25,508
I'd be looking more closely at that hot diode. It may have been damaged, or another part close by may be damaged.

I would be using a resistor (say a 10 ohm 20W resistor) as my load until I knew what was happening (if that doesn't work, try your battery in series with that resistor).

#### Woodman

Dec 3, 2012
47
I'd be looking more closely at that hot diode. It may have been damaged, or another part close by may be damaged.

I would be using a resistor (say a 10 ohm 20W resistor) as my load until I knew what was happening (if that doesn't work, try your battery in series with that resistor).

Steve, thanks for your reply again. I don't have any such resistor, but I have many old car dome light type bulbs. Okay if I "charge" bulbs as the load, and should I wait until new diodes arrive to test?

You can test the SCR's with a meter. If they are high voltage ones they won't stay shorted, but low voltage ones will.

Jotto, thanks for the reply also. I have ordered new high voltage SCRs. The bad diode had continuity in any direction tested with a multimeter on the diode setting. The good diodes tested with ohms in one direction and infinite resistance in two other directions. So I'm guessing that one diodes is toast and can no longer block voltages from a live car battery, and this is why when battery is connected diode gets ultra hot? Also not sure of SCR's amp rating of old, but new ones have 12 amps continuous duty.

Since both boards are identical, I tested all twenty some components to see if anything else was wrong:

1.The two smaller diodes test same on both boards
2. All the resistors were within 10% tolerances
3. Three unknown transistors test the same
4. One of four power transistors on the good circuit board tested "leaky" -when compared to same measurement on the other board the good power transistor showed infinite ohms when tested in the diode mode. Of the eight total power transistors this was the only one that tested leaky and it is located on the charger that works.
Now I'm wondering if I should order a replacement power transistor. Ebay sells generic power transistors. Not sure if they will work, and if all four should be replaced??

Woody

UPDATE: I found some numbers on back of power transistors and ordered exact replacement. Interestingly, three of the four power transistors on the two boards are different models. The one that is leaky has only 40 volt max transistors, while the other board has all 150 volt maximum capacity.

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#### (*steve*)

##### ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd
Moderator
Jan 21, 2010
25,508
Yes, a 12V lamp is a good substitute for a resistor.

40V and 150W are two different things. They may be 40V AND 150W

#### Woodman

Dec 3, 2012
47
Yes, a 12V lamp is a good substitute for a resistor.

40V and 150W are two different things. They may be 40V AND 150W

Thanks for noting mistake. I highlighted and corrected in above post to 40 volt and 120 volt. Looks like this charger needs to see voltage from battery before it will output amps. Anyway to override this safety feature?

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#### Woodman

Dec 3, 2012
47
If anyone ever wants a picture of how board is supposed to look like here are pics front and back. It is complicated circuit having 13 resistors, 4 power transistors, 3 regular transistors, 2 SCRs, a pair of 1n4007 diodes, and a voltage regulator diode. Part numbers are on each component.

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#### (*steve*)

##### ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd
Moderator
Jan 21, 2010
25,508
I highlighted and corrected in above post to 40 volt and 120 volt.

That makes a lot more sense.

The transistors probably only need to be rated at 40V. Maybe they ran out, or someone used the wrong part, or... (who knows)

The lower voltage transistor probably performs better in the usual case.

Looks like this charger needs to see voltage from battery before it will output amps. Anyway to override this safety feature?

Place the lamp in series with your battery. The lamp will (help) prevent damaging currents from flowing either from the charger to the battery or vice versa. (I think I mentioned this very briefly above, but I didn't think you'd need to do it).

#### Woodman

Dec 3, 2012
47
Place the lamp in series with your battery. The lamp will (help) prevent damaging currents from flowing either from the charger to the battery or vice versa. (I think I mentioned this very briefly above, but I didn't think you'd need to do it).

Steve, understood what you said the first time -the fuse/light would blow if amps were too high thereby protecting BAT and charger. What my question was, and I admit it was not at all asked very clearly, how to override the safety feature by altering the circuit board? This would be useful if using charger for another purpose like a power supply for bench testing or electroplating. I suppose easiest way would be to bypass circuit board completely and take voltages directly from the transformer, then bridge rectify it, and somehow use caps/resistors for smoother DC?
Today I took voltage measurements on this center-taped secondary and found six different voltages ranging from about eight to 25 volts, and was thinking this could make a nice "stepping" power supply, especially since I have an extra one. Any suggestions on moding this to a PS?

Thanks,
Woody

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#### Woodman

Dec 3, 2012
47
I'd be looking more closely at that hot diode. It may have been damaged, or another part close by may be damaged.

Steve, the SCR diode finally arrived and has been replaced. When tested on a spare shorted 12 volt battery, the charger seemed to function just like the other working battery charger (it chargers until reaches 14.4 volts, then turns off until it falls to 13.88 volts, then restarts charging, and it loops this process continuosly). So at least it appears to be working now.
Any luck deciphering the diagram?

Woody

Note: 2 amp setting is better for temporarily maintaining a battery once it starts maintenance cycle.

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#### (*steve*)

##### ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd
Moderator
Jan 21, 2010
25,508
The circuit is sufficiently non-trivial that I need to spend some time looking at it

Unfortunately work prior to Christmas was hectic and well, it's nearing the end of Christmas day now... Not an un-busy time of the year at home.

I think that it's unlikely you could change this into a power supply without completely changing the circuit, battery chargers and power supplies are quite different beasts.

The idea of the lamp in series with the battery is simply to limit the current to a safe value. At the voltages normally applied, you would never blow it.

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