Connected quadruple excitations in the coupled-cluster theory
The role of the connected quadruple excitations in the coupled-cluster (CC) theory is discussed. The full inclusion of the T 4 (Q) operator in addition to singles (S), doubles (D) and triples (T) defines the CCSDTQ method which offers a very accurate computational tool applicable to small molecular...
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Published in | Molecular physics Vol. 108; no. 21-23; pp. 2975 - 2985 |
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Main Authors | , |
Format | Journal Article |
Language | English |
Published |
Abingdon
Taylor & Francis Group
10.11.2010
Taylor & Francis Ltd Taylor & Francis |
Subjects | |
Online Access | Get full text |
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Summary: | The role of the connected quadruple excitations in the coupled-cluster (CC) theory is discussed. The full inclusion of the T
4
(Q) operator in addition to singles (S), doubles (D) and triples (T) defines the CCSDTQ method which offers a very accurate computational tool applicable to small molecular systems. The efficient organization of the CC equations results in the quasilinear formulation of the CCSDTQ scheme. A wider range of applications can be ensured with the approximate variants of the CCSDTQ approach. Due to possible factorization of the lowest order quadruple contribution to the energy, a noniterative scheme has been formulated which requires n
7
scaling. Performance of the CCSDTQ method has been discussed on the basis of the results obtained for several small molecules in confrontation with the reference full configuration interaction data. |
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Bibliography: | ObjectType-Article-2 SourceType-Scholarly Journals-1 ObjectType-Feature-1 content type line 23 |
ISSN: | 0026-8976 1362-3028 |
DOI: | 10.1080/00268976.2010.523523 |