Extension of the CC($P$;$Q$) Formalism to the Electron Attachment and Ionization Potential Equation-of-Motion Coupled-Cluster Frameworks

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Main Authors: Gururangan, Karthik, Yuwono, Stephen H., DePrince III, A. Eugene, Piecuch, Piotr
Format: Preprint
Published: 2025
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author Gururangan, Karthik
Yuwono, Stephen H.
DePrince III, A. Eugene
Piecuch, Piotr
author_facet Gururangan, Karthik
Yuwono, Stephen H.
DePrince III, A. Eugene
Piecuch, Piotr
contents We combine the electron attachment (EA) and ionization potential (IP) equation-of-motion (EOM) coupled-cluster (CC) approaches with the CC($P$;$Q$) formalism. The resulting methodologies are used to describe the electronic states of several open-shell molecules, with the goal of approximating high-level EA/IP-EOMCC energetics corresponding to a full treatment of 3-particle-2-hole (3$p$-2$h$) and 3-hole-2-particle (3$h$-2$p$) excitations on top of CC with singles and doubles (CCSD). We show that the active-orbital-based EA/IP-EOMCC CC($P$;$Q$) approaches, abbreviated as EA/IP-CC(t;3), achieve sub-millihartree accuracies relative to the parent EA-EOMCCSD(3$p$-2$h$)/IP-EOMCCSD(3$h$-2$p$) data using reduced computational effort, while improving upon their completely renormalized EA/IP-CR-EOMCC(2,3) counterparts.
format Preprint
id arxiv_https___arxiv_org_abs_2506_16320
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Extension of the CC($P$;$Q$) Formalism to the Electron Attachment and Ionization Potential Equation-of-Motion Coupled-Cluster Frameworks
Gururangan, Karthik
Yuwono, Stephen H.
DePrince III, A. Eugene
Piecuch, Piotr
Chemical Physics
Computational Physics
We combine the electron attachment (EA) and ionization potential (IP) equation-of-motion (EOM) coupled-cluster (CC) approaches with the CC($P$;$Q$) formalism. The resulting methodologies are used to describe the electronic states of several open-shell molecules, with the goal of approximating high-level EA/IP-EOMCC energetics corresponding to a full treatment of 3-particle-2-hole (3$p$-2$h$) and 3-hole-2-particle (3$h$-2$p$) excitations on top of CC with singles and doubles (CCSD). We show that the active-orbital-based EA/IP-EOMCC CC($P$;$Q$) approaches, abbreviated as EA/IP-CC(t;3), achieve sub-millihartree accuracies relative to the parent EA-EOMCCSD(3$p$-2$h$)/IP-EOMCCSD(3$h$-2$p$) data using reduced computational effort, while improving upon their completely renormalized EA/IP-CR-EOMCC(2,3) counterparts.
title Extension of the CC($P$;$Q$) Formalism to the Electron Attachment and Ionization Potential Equation-of-Motion Coupled-Cluster Frameworks
topic Chemical Physics
Computational Physics
url https://arxiv.org/abs/2506.16320