Document Type

Article

Publication Date

4-2018

Abstract

We study the performance of the two-determinant (TD) coupled-cluster (CC) method which, unlike conventional ground-state single-reference (SR) CC methods, can, in principle, provide a naturally spin-adapted treatment of the lowest-lying open-shell singlet (OSS) and triplet electronic states. Various choices for the TD-CC reference orbitals are considered, including those generated by the multi-configurational self-consistent field method. Comparisons are made with the results of high-level SR-CC, equation-of-motion (EOM) CC, and multi-reference EOM calculations performed on a large test set of over 100 molecules with low-lying OSS states. It is shown that in cases where the EOMCC reference function is poorly described, TD-CC can provide a significantly better quantitative description of OSS total energies and OSS-triplet splittings.

Comments

© 2018 Author(s), published under an exclusive license with American Institute of Physics.

AFIT Scholar, as the repository of the Air Force Institute of Technology, furnishes the published Version of Record for this article in accordance with the sharing policy of the publisher, AIP Publishing. A 12-month embargo was observed.

This article may be downloaded for personal use only. Any other use requires prior permission of the author and AIP Publishing. This article appeared in The Journal of Chemical Physics, 148: 164102 as fully cited below and may be found at DOI: 10.1063/1.5025170.

Funding notes: This work was supported by funding from the U.S. DoD High Performance Computing Modernization Program and a grant of computer time at the U.S. Air Force Research Laboratory DoD Supercomputing Research Center.

A 'Supplementary Material' file for this article is provided at the AIP website.

This article was chosen as an AIP Editor's Pick.

DOI

10.1063/1.5025170

Source Publication

The Journal of Chemical Physics

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