Necessary Duration of Molecular Dynamics Simulation for Calculation of Self-Diffusion Coefficient during Migration of Different Point Defects in Nickel
The evaluation of the necessary duration of molecular dynamics experiment for the calculation of the selfdiffusion coefficient during migration of different point defects in Ni (vacancy, bivacancy, self-interstitial atom, hydrogen atom) is conducted in this paper. The mentioned defects have different mobility that results in different intensities of atoms displacements caused by migration of the defect. The accuracy of diffusion coefficient calculation is related to the accuracy of estimation of root-mean-square changes of atoms coordinates. Consequently, the accuracy increases with the increase of molecular-dynamic experiment duration t, the temperature T, and the mobility of the defect initiating the diffusion. To describe the interatomic interactions, the multi-particle Cleri-Rosato potential is used in the study. It is shown that the simulation duration of 100 ps is enough to calculate the diffusion coefficient when the temperature is higher than 0.6 of melting point. When calculating the diffusion coefficient of impurity in a metal crystal (for example, the hydrogen impurity), it is possible to decrease the root mean square error of displacement evaluation of impurity atoms by increasing the number of impurity atoms.