Optimization and Parallelization of DFT and TDDFT in GAMESS on DoD HPC Machines

The quantum chemistry package General Atomic and Molecular Electronic Structure System (GAMESS) is employed in the first-principles modeling of complex molecular systems by using the density functional theory (DFT) as well as a number of other post-Hartree-Fock (HF) methods. Both DFT and time-dependent DFT (TDDFT) are of particular interest to the Department of Defense (DoD) Computational Biology, Chemistry, and Materials Science (CCM). Millions of CPU hours per year are expended by GAMESS calculations on DoD high performance computing (HPC) systems. Therefore, any reduction in wall-clock time for these calculations will represent a significant saving in CPU hours. As part of this work, three areas for improvement were identified: 1) replacement of the exchange-correlation (XC) integration grid, 2) TDDFT parallelization, and 3) profiling and optimization of the DFT and TDDFT. We summarize the work performed in these task areas and present the resulting speed-up. Our software enhancements are available to the general public in the 11APR2008R1 version of GAMESS.