Massively Parallel MP2-F12 Calculations on the K Computer

A hybrid MPI/OpenMP parallel code of the explicitly correlated second-order MOller-Plesset perturbation theory (MP2-F12) is implemented into the GELLAN program for massively parallel computations on the K computer in Japan. Various many-electron integrals are generated using numerical quadrature techniques. For integral evaluation and transformation, we distribute the grid points to MPI processes to reduce the operation count and memory requirement. Operations over grid points are efficiently performed by the matrix-matrix product library (DGEMM). This numerical MP2-F12 program achieves more than 30% of the peak performance of the K computer and the calculation of C60 with aug-cc-pVTZ basis set finishes in less than 15 min using 8148 nodes (65,184 cores) of the K computer. The implementation enables us to use MP2-F12/aug-cc-pVTZ level of theory routinely for large molecules such as organic photovoltaics and electronic materials. (c) 2014 Wiley Periodicals, Inc.