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Equation-of-Motion Coupled-Cluster Method with Double Electron-Attaching Operators: Theory, Implementation, and Benchmarks

preprint
revised on 24.12.2020, 07:38 and posted on 28.12.2020, 06:51 by Sahil Gulania, Eirik Fadum Kjønstad, John F. Stanton, Henrik Koch, Anna Krylov

We report a production-level implementation of equation-of-motion coupled-cluster method with double electron- attaching EOM operators of 2p and 3p1h types, EOM-DEA-CCSD. This ansatz, suitable for treating electronic structure patterns that can be described as two-electrons-in-many orbitals, represents a useful addition to EOM-CC family of methods. We analyze the performance of EOM-DEA-CCSD for energy differences and molecular properties. By considering reduced quantities, such as state and transition one-particle density matrices, we can compare EOM-DEA- CCSD wave-functions with wave-functions computed by other EOM-CCSD methods. The benchmarks illustrate that EOM-DEA-CCSD capable of treating diradicals, bond-breaking, and some types of conical intersection.

History

Email Address of Submitting Author

gulania@usc.edu

Institution

University of Southern California

Country

USA

ORCID For Submitting Author

0000-0001-7918-6669

Declaration of Conflict of Interest

A.I.K. is the president and a part-owner of Q-Chem, Inc.

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