Atomistic Simulations on Scalar and Vector Computers

Large scale atomistic simulations are feasible only with classical effective potentials. Nevertheless, even for classical simulations some ab-initio computations are often necessary, e.g. for the development of potentials or the validation of the results. Ab-initio and classical simulations use rather different algorithms and make different requirements on the computer hardware. We present performance comparisons for the DFT code VASP and our classical molecular dynamics code IMD on different computer architectures, including both clusters of microprocessors and vector computers. VASP performs excellently on vector machines, whereas IMD is better suited for large clusters of microprocessors. We also report on our efforts to make IMD perform well even on vector machines.