Spin component scaling in multiconfiguration perturbation theory

A. Szabados, Péter Nagy

Research output: Article

9 Citations (Scopus)

Abstract

We investigate a term-by-term scaling of the second-order energy correction obtained by perturbation theory (PT) starting from a multiconfiguration wave function. The total second-order correction is decomposed into several terms, based on the level and the spin pattern of the excitations. To define individual terms, we extend the same spin/different spin categorization of spin component scaling in various ways. When needed, identification of the excitation level is facilitated by the pivot determinant underlying the multiconfiguration PT framework. Scaling factors are determined from the stationary condition of the total energy calculated up to order 3. The decomposition schemes are tested numerically on the example of bond dissociation profiles and energy differences. We conclude that Grimme's parameters determined for single-reference Møller-Plesset theory may give a modest error reduction along the entire potential surface, if adopting a multireference based PT formulation. Scaling factors obtained from the stationary condition show relatively large variation with molecular geometry, at the same time they are more efficient in reducing the error when following a bond dissociation process.

Original languageEnglish
Pages (from-to)523-534
Number of pages12
JournalJournal of Physical Chemistry A
Volume115
Issue number4
DOIs
Publication statusPublished - febr. 3 2011

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perturbation theory
scaling
Wave functions
dissociation
Decomposition
pivots
Geometry
determinants
excitation
energy
wave functions
decomposition
formulations
profiles
geometry

ASJC Scopus subject areas

  • Physical and Theoretical Chemistry

Cite this

Spin component scaling in multiconfiguration perturbation theory. / Szabados, A.; Nagy, Péter.

In: Journal of Physical Chemistry A, Vol. 115, No. 4, 03.02.2011, p. 523-534.

Research output: Article

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