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Coupled‐cluster method for an incomplete model space
Author(s) -
Kucharski Stanislaw A.,
Bartlett Rodney J.
Publication year - 1992
Publication title -
international journal of quantum chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.484
H-Index - 105
eISSN - 1097-461X
pISSN - 0020-7608
DOI - 10.1002/qua.560440810
Subject(s) - normalization (sociology) , subspace topology , hilbert space , coupled cluster , cluster (spacecraft) , valence (chemistry) , space (punctuation) , statistical physics , mathematics , physics , theoretical physics , computer science , pure mathematics , mathematical analysis , quantum mechanics , molecule , sociology , anthropology , programming language , operating system
The coupled‐cluster method with multidimensional reference space is studied in the case of the incomplete active space ( IAS ). The latter was chosen as a subspace of the Hilbert space corresponding to a fixed number of valence particles. Two different approaches for the normalization condition are analyzed. When not imposing intermediate normalization, the cancellation of disconnected terms is proven, ensuring that extensive energies are obtained. © 1992 John Wiley & Sons, Inc.