One-Body Properties and Their Perturbative Accuracy with Aufbau Suppressed Coupled Cluster Theory

TL;DR

This paper develops a method to compute one-body properties using Aufbau suppressed coupled cluster theory, improving the accuracy of excited state descriptions and properties like dipole moments.

Contribution

The authors derived and implemented a new approach to calculate one-body properties within Aufbau suppressed coupled cluster theory, enhancing excited state analysis.

Findings

ASCC accuracy matches linear response and EOM-CC for dipole moments in small molecules

Iterative natural orbital basis refinement reduces dependence on initial orbitals

Method provides reliable excited state properties with perturbative completeness

Abstract

We derived and implemented the calculation of the one-body reduced density matrix for Aufbau suppressed coupled cluster theory, from which excited state natural orbitals and one-body properties, like atomic populations and dipole moments, are obtained. We utilized the natural orbitals to refine the ASCC solution for simple valence and Rydberg systems, exploring the process of repeatedly solving the ASCC equations in successive natural orbital bases to achieve independence from the starting molecular orbitals. For dipole moments in small molecules where high-level comparison data is available, we find that the accuracy of ASCC essentially matches that of linear response and equation-of-motion coupled cluster as long as care is taken to preserve the response's perturbative completeness.