Exploiting Non-Abelian Point-Group Symmetry to Estimate the Exact Ground-State Correlation Energy of Benzene in a Polarized Split-Valence Triple-Zeta Basis Set

TL;DR

This paper introduces a method to utilize non-Abelian point-group symmetry in local electronic-structure calculations, significantly improving the accuracy and efficiency of estimating the ground-state correlation energy of benzene.

Contribution

It demonstrates how to enforce symmetry among localized orbitals using a recent unitary protocol, leading to high-accuracy energy estimates and computational savings in local correlation methods.

Findings

Achieved high-accuracy ground-state energy for benzene with symmetry enforcement.

Showed computational savings proportional to the inverse of the point group order.

Validated the approach within many-body expanded full configuration interaction (MBE-FCI) theory.

Abstract

Local electronic-structure methods in quantum chemistry operate on the ability to compress electron correlations more efficiently in a basis of spatially localized molecular orbitals than in a parent set of canonical orbitals. However, many typical choices of localized orbitals tend to be related by selected, near-exact symmetry operations whenever a molecule belongs to a point group, a feature which remains largely unexploited in most local correlation methods. The present Letter demonstrates how to leverage a recent unitary protocol for enforcing symmetry properties among localized orbitals to yield a high-accuracy estimate of the exact ground-state correlation energy of benzene ($D_{6h}$) in correlation-consistent polarized basis sets of both double- and triple-$\zeta$ quality. Through an initial application to many-body expanded full configuration interaction (MBE-FCI) theory, we show how molecular point-group symmetry can lead to computational savings that are inversely proportional to the order of the point group in a manner generally applicable to the acceleration of modern local correlation methods.