Monte Carlo configuration interaction with perturbation corrections for dissociation energies of first row diatomic molecules: C2, N 2, O2, CO, and NO

Thomas P. Kelly, Ajith Perera, Rodney J. Bartlett, James C. Greer

Research output: Journal PublicationArticlepeer-review

18 Citations (Scopus)

Abstract

Dissociation energies for the diatomic molecules C2, N 2, O2, CO, and NO are estimated using the Monte Carlo configuration interaction (MCCI) and augmented by a second order perturbation theory correction. The calculations are performed using the correlation consistent polarized valence "triple zeta" atomic orbital basis and resulting dissociation energies are compared to coupled cluster calculations including up to triple excitations (CCSDT) and Full Configuration Interaction Quantum Monte Carlo (FCIQMC) estimates. It is found that the MCCI method readily describes the correct behavior for dissociation for the diatomics even when capturing only a relatively small fraction (∼80%) of the correlation energy. At this level only a small number of configurations, typically O(10 3) from a FCI space of dimension O(1014), are required to describe dissociation. Including the perturbation correction to the MCCI estimates, the difference in dissociation energies with respect to CCSDT ranges between 1.2 and 3.1 kcal/mol, and the difference when comparing to FCIQMC estimates narrows to between 0.5 and 1.9 kcal/mol. Discussions on MCCI's ability to recover static and dynamic correlations and on the form of correlations in the electronic configuration space are presented.

Original languageEnglish
Article number084114
JournalJournal of Chemical Physics
Volume140
Issue number8
DOIs
Publication statusPublished - 28 Feb 2014
Externally publishedYes

ASJC Scopus subject areas

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

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