GAMMCOR

GammCor performs calculations of interaction energies for ground- and excited-state multireference wave functions, and range-separated multiconfiguration DFT energy with the long-range-AC/AC0 correlation correction.

TUL (Lodz, Poland), University of Warsaw (Poland)

GammCor performs calculations of interaction energies using multireference symmetry adapted perturbation theory method (for ground and excited states), the adiabatic connection (AC and AC0) correlation energy for ground- and excited-state multireference wave functions, and range-separated multiconfiguration DFT energy with the long-range-AC/AC0 correlation correction. All the implemented multireference methods rely only on one- and two-electron reduced density matrices, which are computed externally. GammCor is an open-source program licensed under GNU GPLv3.

Audience

Theoretical chemistry community, quantum simulation of materials community.

Current Stage and Next Steps

Status at December 2021: Improved vectorization, efficient linear algebra libraries are used which enabled partial parallelization. Novel computational algorithms have been developed, implemented, and tested. These include: efficient algorithms for handling two-electron integrals (in terms of both storage and I/O operations), new computational algorithms for intermolecular interaction calculations with improved numerical stability and better scaling with the system size, computational algorithms for electron correlation calculations based on the Cholesky decomposition of two-electron integrals. 

Next Steps: improvements in code portability, parallelization, taking full advantage of the Cholesky decomposition in construction of the bottleneck intermediates, further performance optimization (I/O operations and memory handling), tests for larger systems, decreasing the disk usage by direct evaluation of two electron integrals in Cholesky decomposition routines.