Improving Aufbau Suppressed Coupled Cluster Through Perturbative Analysis

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Hauptverfasser: Tuckman, Harrison, Ma, Ziheng, Neuscamman, Eric
Format: Preprint
Veröffentlicht: 2025
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author Tuckman, Harrison
Ma, Ziheng
Neuscamman, Eric
author_facet Tuckman, Harrison
Ma, Ziheng
Neuscamman, Eric
contents Guided by perturbative analysis, we improve the accuracy of Aufbau suppressed coupled cluster theory in simple single excitations, multi-configurational single excitations, and charge transfer excitations while keeping the cost of its leading-order terms precisely in line with ground state coupled cluster. Combining these accuracy improvements with a more efficient implementation based on spin-adaptation, we observe high accuracy in a large test set of single excitations, and, in particular, a mean unsigned error for charge transfer states that outperforms equation-of-motion coupled cluster theory by 0.25 eV. We discuss how these results are achieved via a systematic identification of which amplitudes to prioritize for single- and multi-configurational excited states, and how this prioritization differs in important ways from the ground state theory. In particular, our data show that a partial linearization of the theory increases accuracy by mitigating unwanted side effects of Aufbau suppression.
format Preprint
id arxiv_https___arxiv_org_abs_2501_10515
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Improving Aufbau Suppressed Coupled Cluster Through Perturbative Analysis
Tuckman, Harrison
Ma, Ziheng
Neuscamman, Eric
Chemical Physics
Guided by perturbative analysis, we improve the accuracy of Aufbau suppressed coupled cluster theory in simple single excitations, multi-configurational single excitations, and charge transfer excitations while keeping the cost of its leading-order terms precisely in line with ground state coupled cluster. Combining these accuracy improvements with a more efficient implementation based on spin-adaptation, we observe high accuracy in a large test set of single excitations, and, in particular, a mean unsigned error for charge transfer states that outperforms equation-of-motion coupled cluster theory by 0.25 eV. We discuss how these results are achieved via a systematic identification of which amplitudes to prioritize for single- and multi-configurational excited states, and how this prioritization differs in important ways from the ground state theory. In particular, our data show that a partial linearization of the theory increases accuracy by mitigating unwanted side effects of Aufbau suppression.
title Improving Aufbau Suppressed Coupled Cluster Through Perturbative Analysis
topic Chemical Physics
url https://arxiv.org/abs/2501.10515