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Direct restricted‐step MCSCF calculations on the structure and spectrum of cyclobutadiene
Author(s) -
Ågren H.,
Correia N.,
FloresRiveros A.,
Jensen H. J. AA.
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.560280823
Subject(s) - cyclobutadiene , excited state , ground state , chemistry , singlet state , adiabatic process , atomic physics , computational chemistry , potential energy , triplet state , maxima and minima , molecule , physics , quantum mechanics , organic chemistry , mathematical analysis , mathematics
The structure of cyclobutadiene in the ground 1 A 9 state and the lowest excited 3 B 1 g , 1 A 1 g , and 1 B 1 g , states are investigated by means of a direct, step‐restricted, second order MCSCF method. The barrier height for interconversion between the rectangular forms of the ground state minima is predicted to be 6.2kcal/mol and the singlet‐triplet state separation at the ground state square confirmation is predicted to be 9.7 kcal/mol. All investigated excited states are fond to have square equilibrium geometry the and adiabatic transition energy to the 1 A 1 g , state is predicted to be lower than that to the 1 B 1 g , state.