Performance Tests and Improvements on the rmcdhf and rci Programs of GRASP

The latest published version of GRASP (General-purpose Relativistic Atomic Structure Package), i.e., GRASP2018, retains a few suboptimal subroutines/algorithms, which reflect the limited memory and file storage of computers available in the 1980s. Here we show how the efficiency of the relativistic self-consistent-field (SCF) procedure of the multiconfiguration-Dirac-Hartree-Fock (MCDHF) method and the relativistic configuration-interaction (RCI) calculations can be improved significantly. Compared with the original GRASP codes, the present modified version reduces the CPU times by factors of a few tens or more. The MPI performances for all the original and modified codes are carefully analyzed. Except for diagonalization, all computational processes show good MPI scaling.

Automated summary

The latest version of GRASP2018 has suboptimal subroutines/algorithms due to the computer limitations in the 1980s. This study presents a modification on the relativistic self-consistent-field procedure and configuration-interaction calculations, significantly improving their efficiency. The modified GRASP version reduces CPU times by several tens or more. MPI performances of all codes are analyzed, showing good scaling except for diagonalization.