A parallel order-N tight-binding molecular dynamics program

Tight-binding approaches have been used for many years to calculate the forces between atoms for molecular dynamics simulations. Even though the interactions are localized, dense matrix solvers were typically used on the sparse matrices. This limited the system sizes to typically a few hundred atoms due to the N^3 scaling. The Variational Density Matrix method [1] is a localized quantum mechanical approach that provides the same forces with order-N scaling. This method is also very naturally parallel, making it possible to spread simulations across a very large number of processors. This presentation will discuss the optimization and parallelization strategies needed to provide efficient scaling on a variety of massively parallel systems and cluster computers. Samples of some of the science that can now be attacked will also be presented. [1] X.-P. Li, R.W. Nunes, and David Vanderbilt, "A Density-Matrix Electronic-Structure Method with Linear System-Size Scaling," Physical Review B 47, 10891 (1993).