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Calculation of excited‐state properties of some small molecules: Comparative study of the CNDO /S and CNDO /2‐ v n −1 potential methods
Author(s) -
Sannigrahi A. B.,
Mukherjee D. C.,
De B. R.
Publication year - 1983
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.560230502
Subject(s) - cndo/2 , excited state , chemistry , ab initio , ab initio quantum chemistry methods , computational chemistry , molecule , atomic physics , physics , organic chemistry
The transition energy and geometry of the lowest excited ( n π*) singlet and triplet states of CO, CS, HNO, H 2 CO, HFCO, and F 2 CO molecules are calculated by CNDO /S and CNDO /2‐ V N −1 potential methods, and the results are compared with those of experimental and ab initio theoretical studies, wherever available. In the calculation of the vertical transition energy, the performance of the CNDO /S method is seen to be generally more satisfactory than that of the CNDO /2‐ V N −1 potential method, while the reverse is true for the excited‐state geometry. The CNDO /S method as such fails to describe the geometry of the excited state, but a combined version ( CNDO /S‐2) of CNDO /S and CNDO /2, as well as the CNDO /2‐ V N −1 potential method is fairly successful in this regard.