This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Although a number of faster basic molecular dynamics (MD) algorithms exist, none have nearly as many fully implemented sampling methods as CHARMM. The advanced sampling methods in CHARMM are critical for meaningful molecular simulation, especially for large biomolecules. Improvement of the parallel implementation of the CHARMM MD engine to fully take advantage of modern massively parallel architecture will allow CHARMM to match the performance of other top MD programs. We need more large supercomputer resources and architectures to test and develop the algorithm. Our specific scientific project (carbohydrate modeling) and the larger CHARMM user community will greatly benefit from this development. Carbohydrate modeling connects to one of our large SciDAC grants to understand the biochemical mechanism in enzyme-catalyzed cellulose degradation, in which carbohydrate recognition and glycosylation play important roles.