Perturbative approximations to single and double spin flip equation of motion coupled cluster singles doubles methods

TitlePerturbative approximations to single and double spin flip equation of motion coupled cluster singles doubles methods
Publication TypeJournal Article
Year of Publication2013
AuthorsDutta, AKumar, Pal, S, Ghosh, D
JournalJournal of Chemical Physics
Volume139
Issue12
Pagination124116
Date PublishedSEP
ISSN0021-9606
Abstract

Spin flip equation of motion coupled cluster (EOM-SF-CC) can correctly treat situations involving electronic degeneracies or near degeneracies, e. g., bond breaking, di- and tri-radicals, etc. However, for large systems EOM-SF-CC (even in single and double excitations) is computationally prohibitively expensive. Therefore, earlier approximations to EOM-SF-CC methods such as spin flip configuration interaction singles with perturbative doubles (SF-CIS(D)) have been proposed. In this work, we present a new perturbative approximation to EOM-SF-CC, which has been found to be more accurate than SF-CIS(D). The capabilities, advantages, and timings of the new approach have been demonstrated considering the singlet-triplet gaps in di- and triradicals as well as bond breaking examples. The method is extended to double spin flip EOM-CC and its capabilities have been tested. (C) 2013 AIP Publishing LLC.

DOI10.1063/1.4821936
Type of Journal (Indian or Foreign)Foreign
Impact Factor (IF)3.122
Divison category: 
Physical and Materials Chemistry