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A pair‐excitation MCSCF calculation based on CNDO / INDO approximation I
Author(s) -
Kumakura Shigekazu,
Shiraishi Satoshi,
Izawa Masaru,
Hanamura Mitsuyasu
Publication year - 1992
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.560410604
Subject(s) - cndo/2 , chemistry , excitation , atomic orbital , molecule , computational chemistry , atomic physics , configuration interaction , molecular orbital , complete active space , quantum mechanics , physics , organic chemistry , electron
Second‐order multiconfigurational self‐consistent field ( MCSCF ) calculation has been programmed on the basis of CNDO / INDO molecular orbital bases, in which the configuration space employed is restricted within pair‐excitations. Test calculations have been carried out for 17 small molecules. All the MCSCF ground states of these molecules have been successfully converged to their respective optimal states by employing a simple weighting scheme. This procedure provides a great savings in computer time. The MCSCF calculation on azetidine required only 27 min on a HITAC M‐680H. The MCSCF energies of HF, F 2 , and BH show improved behaviors up to large atomic distances (∼7au).