Equation-of-motion coupled-cluster methods for ionized states with an approximate treatment of triple excitations

Yannick J. Bomble, Jamal C. Saeh, John F. Stanton, Ṕter G. Szalay, Mihály Kállay, Jürgen Gauss

Research output: Contribution to journalArticle

31 Citations (Scopus)

Abstract

The accuracy of geometries and harmonic vibrational frequencies is evaluated for two equation-of-motion ionization potential coupled-cluster methods including CC3 and CCSDT-3 triples corrections. The first two ∑ states and first ∏ state of the N2+, CO+, CN, and BO diatomic radicals are studied. The calculations show a tendency for the CC3 variant to overestimate the bond lengths and to underestimate the vibrational frequencies, while the CCSDT-3 variant seems to be more reliable. It is also demonstrated that the accuracy of such methods is comparable to sophisticated traditional multireference approaches and the full configuration interaction method.

Original languageEnglish
Article number154107
JournalJournal of Chemical Physics
Volume122
Issue number15
DOIs
Publication statusPublished - Apr 15 2005

ASJC Scopus subject areas

  • Physics and Astronomy(all)
  • Physical and Theoretical Chemistry

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