Explicitly correlated formalism for second-order single-particle Green's function

TL;DR

This paper introduces an explicitly correlated formalism for the GF2 method that improves ionization potential calculations in organic molecules by reducing basis set errors at lower computational cost.

Contribution

It develops a new GF2-F12 formalism that avoids the diagonal approximation and accurately models energy dependence of correlated terms.

Findings

GF2-F12 significantly reduces basis set errors in ionization potentials.

GF2-F12 outperforms GF2 with larger basis sets at lower computational cost.

Method is effective for small and medium organic molecules.

Abstract

We present an explicitly correlated formalism for the second-order single-particle Green's function method (GF2-F12) that does not assume the popular diagonal approximation, and describes the energy dependence of the explicitly correlated terms. For small and medium organic molecules the basis set errors of ionization potentials of GF2-F12 are radically improved relative to GF2: the performance of GF2-F12/aug- cc-pVDZ is better than that of GF2/aug-cc-pVQZ, at a significantly lower cost.