posted on 2021-12-02, 19:06authored byDaniel Mejia-Rodriguez, Alexander Kunitsa, Edoardo Aprà, Niranjan Govind
We
present a scalable implementation of the GW approximation
using Gaussian atomic orbitals to study the valence
and core ionization spectroscopies of molecules. The implementation
of the standard spectral decomposition approach to the screened-Coulomb
interaction, as well as a contour-deformation method, is described.
We have implemented both of these approaches using the robust variational
fitting approximation to the four-center electron repulsion integrals.
We have utilized the MINRES solver with the contour-deformation approach
to reduce the computational scaling by 1 order of magnitude. A complex
heuristic in the quasiparticle equation solver further allows a speed-up
of the computation of core and semicore ionization energies. Benchmark
tests using the GW100 and CORE65 data sets and the carbon 1s binding
energy of the well-studied ethyl trifluoroacetate, or ESCA molecule,
were performed to validate the accuracy of our implementation. We
also demonstrate and discuss the parallel performance and computational
scaling of our implementation using a range of water clusters of increasing
size.