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A linear response, coupled‐cluster theory for excitation energy
Author(s) -
Sekino Hideo,
Bartlett Rodney J.
Publication year - 1984
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.560260826
Subject(s) - coupled cluster , excitation , excited state , diagrammatic reasoning , wave function , relaxation (psychology) , physics , cluster expansion , cluster (spacecraft) , linear response theory , operator (biology) , function (biology) , ground state , equations of motion , quantum electrodynamics , atomic physics , quantum mechanics , statistical physics , chemistry , computer science , condensed matter physics , psychology , social psychology , biochemistry , repressor , evolutionary biology , molecule , biology , transcription factor , gene , programming language
Expressions for static and dynamic properties in coupled‐cluster (CC) theory are derived. In the static case, using diagrammatic techniques, it is shown how consideration of orbital relaxation effects in the theory introduces higher‐order correlation effects. For the dynamic case, excitation energy expressions are obtained without consideration of orbital relaxation effects and shown to be equivalent to an equation of motion (EOM) approach subject to a coupled‐cluster ground‐state wave function and an excitation operator consisting of single and double excitations. Illustrative applications for excited states of ethylene are reported.