Size-consistent self-consistent combination of selected CI and perturbation theory

The present work proposes a consistent combination of two recently reported computational schemes, namely a size-consistent selected CI and a non-divergent second-order perturbation evaluation. The method treats large doubles (and any set of higher excited determinants) in a variational manner and t...

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Bibliographic Details
Published inChemical physics letters Vol. 218; no. 3; pp. 276 - 282
Main Authors Meller, J., Heully, J.L., Malrieu, J.P.
Format Journal Article
LanguageEnglish
Published Amsterdam Elsevier B.V 11.02.1994
Elsevier Science
Subjects
Atomic and molecular physics
Electron correlation calculations for atoms and molecules
Electronic structure of atoms, molecules and their ions: theory
Exact sciences and technology
Physics
Water
Polyatomic molecules
Perturbation theory
Ammonia
Inorganic compounds
Correlation energy
Theoretical study
Electron correlation
Configuration interaction
SD CI method
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Summary:The present work proposes a consistent combination of two recently reported computational schemes, namely a size-consistent selected CI and a non-divergent second-order perturbation evaluation. The method treats large doubles (and any set of higher excited determinants) in a variational manner and the small doubles in a perturbative mode, without any unlinked contributions and exactly treating the EPV terms. Strict separability into closed-shell subsystems is ensured if the localized MOs are used. The efficiency of our proposal is illustrated by a few calculations (NH 3 in the DZP basis set, H 2O in the DZ basis set and the water dimer 2(H 2O)).
ISSN:0009-2614
1873-4448
DOI:10.1016/0009-2614(93)E1475-V