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Variational calculation of vibrational energies of triatomic molecules using SCF optimized modes
Author(s) -
Hidalgo Antonio,
Zúñiga José,
Francés José M.,
Bastida Adolfo,
Requena Alberto
Publication year - 1991
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.560400510
Subject(s) - triatomic molecule , hamiltonian (control theory) , chemistry , molecule , normal coordinates , physics , normal mode , classical mechanics , quantum mechanics , mathematics , vibration , mathematical optimization
A self‐consistent field optimization of the vibrational coordinates for nonlinear triatomic molecules is presented. The optimal coordinates are obtained by making a three‐dimensional rotational transformation of the normal modes and determining the rotation angles as those for which the SCF energy is stationary. The utility of the optimized coordinates in full variational calculations of vibrational energies is studied for the molecules of H 2 O, O 3 , H 2 D + , H 2 T + , and D 2 T + . For H 2 O and O 3 , the optimization procedure leads to the local mode representation. It is shown that the use of the optimal coordinates in variational calculations allows a large reduction of the dimension of the Hamiltonian matrix to be diagonalized in order to reach convergence.