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

28 December 2020, Version 2
This content is a preprint and has not undergone peer review at the time of posting.

Abstract

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.

Keywords

EOM-DEA-CCSD
Diradicals
conical intersection
singlet-triplet splitting
multi-reference ab initio

Supplementary materials

Title
Description
Actions
Title
EOM DEA SI
Description
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