Tensor hypercontraction for fully self-consistent imaginary-time GF2 and GWSOX methods: theory, implementation, and role of the Green's function second-order exchange for intermolecular interactions
arxiv(2024)
摘要
We apply tensor hypercontraction (THC) to reduce the computational scaling of
expensive fully self-consistent Green's function methods. We present an
efficient MPI-parallel algorithm and its implementation for evaluating the
correlated second-order exchange term (SOX). This approach enabled us to
conduct the largest fully self-consistent calculations with over 1100 atomic
orbitals (AOs), with negligible errors attributed to THC fitting. Utilizing our
THC implementation for scGW, scGF2, and scGWSOX (GW plus the SOX term iterated
to achieve full Green's function self-consistency), we evaluated energies of
intermolecular interactions. This approach allowed us to circumvent issues
related to reference dependence and ambiguity in energy evaluation, which are
common challenges in non-self-consistent calculations. We demonstrate that scGW
exhibits a slight overbinding tendency for large systems, contrary to the
underbinding observed with non-self-consistent RPA. Conversely, scGWSOX
exhibits a slight underbinding tendency for such systems. This behavior is both
physical and systematic and is caused by exclusion-principle violating diagrams
or corresponding corrections. Our analysis elucidates the role played by these
different diagrams, which is crucial for the construction of rigorous,
accurate, and systematic methods. Finally, we explicitly show that all
perturbative fully self-consistent Green's function methods are size-extensive.
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