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A truncation hierarchy of coupled cluster models of strongly correlated systems based on perfect-pairing references: the singles+doubles models.
MedLine Citation:
PMID:  20886919     Owner:  NLM     Status:  In-Process    
Abstract/OtherAbstract:
Paired, active-space treatments of static correlation are augmented with additional amplitudes to produce a hierarchy of parsimonious and efficient cluster truncations that approximate the total energy. The number of parameters introduced in these models grow with system size in a tractable way: two powers larger than the static correlation model it is built upon: for instance cubic for the models built on perfect pairing, fourth order for a perfect quadruples (PQ) reference, and fifth order for the models built on perfect hextuples. These methods are called singles+doubles (SD) corrections to perfect pairing, PQ, perfect hextuples, and two variants are explored. An implementation of the SD methods is compared to benchmark results for F(2) and H(2)O dissociation problems, the H(4) and H(8) model systems, and the insertion of beryllium into hydrogen. In the cases examined even the quartic number of parameters associated with PQSD is able to provide results which meaningfully improve on coupled-cluster singles doubles (CCSD) (which also has quartic amplitudes) and compete with existing multi-reference alternatives.
Authors:
John A Parkhill; Martin Head-Gordon
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Publication Detail:
Type:  Journal Article    
Journal Detail:
Title:  The Journal of chemical physics     Volume:  133     ISSN:  1089-7690     ISO Abbreviation:  J Chem Phys     Publication Date:  2010 Sep 
Date Detail:
Created Date:  2010-10-04     Completed Date:  -     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  0375360     Medline TA:  J Chem Phys     Country:  United States    
Other Details:
Languages:  eng     Pagination:  124102     Citation Subset:  -    
Affiliation:
Department of Chemistry, University of California, Berkeley, California 94720, USA. john.parkhill@gmail.com
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