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Spin component scaling in multiconfiguration perturbation theory

We investigate a term-by-term scaling of the second order energy correction obtained by perturbation theory (PT) based on a multiconfiguration wavefunction. The total second order correction is decomposed into several terms, based on the level and spin pattern of the excitations. In particular, same spin and different spin double excitations are grouped separately in the spirit of spin component scaling (SeS). Identification of the excitation level is facilitated by the pivot determinant underlying the multiconfiguration PT framework. Scaling factors of the individual terms are determined from the stationary condition of the total energy calculated up to order three. In the single reference framework this procedure has been shown to result scaling factors similar to those applied in Grimme’s SeS-M011er-Plesset method. Several decomposition schemes are tested numerically on the example of bond dissociation profiles. We conclude, that the success of spin component scaling at around equilibrium geometries is not right away transferable to the entire potential surface, even if adopting a multireference based PT formulation

Universitat de Girona. Departament de Química

Universitat de Girona. Institut de Química Computacional

Author: Szabados, Agnes
Date: 2010 July 8
Abstract: We investigate a term-by-term scaling of the second order energy correction obtained by perturbation theory (PT) based on a multiconfiguration wavefunction. The total second order correction is decomposed into several terms, based on the level and spin pattern of the excitations. In particular, same spin and different spin double excitations are grouped separately in the spirit of spin component scaling (SeS). Identification of the excitation level is facilitated by the pivot determinant underlying the multiconfiguration PT framework. Scaling factors of the individual terms are determined from the stationary condition of the total energy calculated up to order three. In the single reference framework this procedure has been shown to result scaling factors similar to those applied in Grimme’s SeS-M011er-Plesset method. Several decomposition schemes are tested numerically on the example of bond dissociation profiles. We conclude, that the success of spin component scaling at around equilibrium geometries is not right away transferable to the entire potential surface, even if adopting a multireference based PT formulation
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Citation: Szabados, A. (2010). Spin component scaling in multiconfiguration perturbation theory. A ’IX Girona Seminar’. Girona: Universitat. [Consulta 7 setembre 2010]. Disponible a: http://hdl.handle.net/10256.1/1735
Document access: http://hdl.handle.net/10256.1/1735
Language: eng
Publisher: Universitat de Girona. Departament de Química
Universitat de Girona. Institut de Química Computacional
Collection: IX Girona Seminar
Rights: Aquest document està subjecte a una llicència Creative Commons: Reconeixement - No comercial - Compartir igual (by-nc-sa)
Rights URI: http://creativecommons.org/licenses/by-nc-sa/3.0/es/deed.ca
Subject: Química quàntica -- Congressos
Quantum chemistry -- Congresses
Title: Spin component scaling in multiconfiguration perturbation theory
Type: info:eu-repo/semantics/lecture
Repository: DUGiMedia

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