Premium
Geminal Localization in the Separated‐Pair Model II. Excited States of the Φ‐Electronic Model of Benzene
Author(s) -
Sengupta S.,
Paldus J.,
C̆íz̆ek J.
Publication year - 2009
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.560060617
Subject(s) - excited state , geminal , hamiltonian (control theory) , coupling constant , chemistry , excitation , configuration interaction , electronic correlation , uncorrelated , benzene , atomic physics , wave function , quantum mechanics , physics , molecular physics , electron , mathematics , stereochemistry , mathematical optimization , statistics , organic chemistry
The separated‐pair model is applied to a study of the correlation effects in the low‐lying excited states of benzene using the Φ‐electron approximation scheme and the Pariser‐Parr‐Pople‐type Hamiltonian. It is shown that the free localizability of geminals is essential for the success of this approach in the case of excited states. The correlation effects in the low‐lying benzene excited states are studied as a function of coupling constant ranging from the fully correlated to the completely uncorrelated limit. For the excitation energies into the B 2 u and E 2 g states, the separated‐pair model yields, over the whole range of the coupling constant, more than 85% of the “exact” value as obtained by the full configuration interaction calculation.