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Analytical gradient of the CIS ( D ) perturbative correction to single‐excitation configuration interaction excited states
Author(s) -
Ishikawa Naoto,
HeadGordon Martin
Publication year - 1995
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.560560845
Subject(s) - configuration interaction , excited state , excitation , energy (signal processing) , multireference configuration interaction , physics , atomic physics , chemistry , spin (aerodynamics) , ground state , quantum electrodynamics , quantum mechanics , thermodynamics
Abstract The complete spin–orbital formulation of the analytical first‐derivative expression of the CIS ( D ) energy correction (doubles correction to the excitation energy from configuration interaction with single substitution, CIS ) is presented. The CIS ( D ) method gives a perturbative correction to the CIS energy (which is roughly analogous to the Hartree–Fock energy for ground states) in a way that resembles second–order Møller–Plesset ( MP 2) theory for ground states. © 1995 John Wiley & Sons, Inc.