The implementation of the multireference coupled-cluster method based on the single-reference formalism

Nevin Oliphant, Ludwik Adamowicz

Research output: Contribution to journalArticle

145 Citations (Scopus)

Abstract

A generalized version of the multireference coupled-cluster method using a single-reference formalism, which we presented in an earlier paper, has been implemented. Any number of determinants, that differ from the formal reference determinant by single or double excitations, can now be included in the reference space. In the present implementation, the single and double excitations from the secondary reference determinants have been truncated to include only those that correspond to triple excitations from the formal reference determinant. Calculations are done on a few model systems, LiH, BH, and H2O, at equilibrium and stretched geometries. Comparisons are made with full configuration interaction (CI) treatment for the single bond stretch in LiH and BH, and the results are quite promising. For the water molecule, comparisons are made with the results obtained with the coupled cluster method truncated at triple excitations (CCSDT), as well as with the full CI results. While the multireference method did not do as well for the simultaneous two-bond stretch in H2O as it did for the single bond cases, it did at least as well as the CCSDT at representing the points on the full CI potential curve.

Original languageEnglish (US)
Pages (from-to)3739-3744
Number of pages6
JournalThe Journal of Chemical Physics
Volume96
Issue number5
StatePublished - 1992

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determinants
formalism
configuration interaction
excitation
Molecules
Geometry
Water
single bond
curves
geometry
water
molecules

ASJC Scopus subject areas

  • Atomic and Molecular Physics, and Optics

Cite this

The implementation of the multireference coupled-cluster method based on the single-reference formalism. / Oliphant, Nevin; Adamowicz, Ludwik.

In: The Journal of Chemical Physics, Vol. 96, No. 5, 1992, p. 3739-3744.

Research output: Contribution to journalArticle

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