Transcorrelated coupled cluster methods

TL;DR

This paper introduces transcorrelated coupled cluster methods that improve basis set convergence and accuracy by applying a similarity transformation with a Jastrow factor, including new approximations for three-body integrals.

Contribution

It presents a novel formulation of coupled cluster methods using a transcorrelated Hamiltonian with a Jastrow factor, enhancing computational accuracy.

Findings

Superior basis set convergence compared to traditional methods

Enhanced accuracy demonstrated in test calculations

Effective approximations for three-body integrals proposed

Abstract

Transcorrelated coupled cluster and distinguishable cluster methods are presented. The Hamiltonian is similarity transformed with a Jastrow factor in the first quantisation, which results in up to three-body integrals. The coupled cluster with singles and doubles equations on this transformed Hamiltonian are formulated and implemented. It is demonstrated that the resulting methods have a superior basis set convergence and accuracy to the corresponding conventional and explicitly correlated methods. Additionally, approximations for three-body integrals are suggested and tested.