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Optimization of conical intersections using the semiempirical MNDOC–CI method with analytic gradients
Author(s) -
Izzo Roberto,
Klessinger Martin
Publication year - 2000
Publication title -
journal of computational chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.907
H-Index - 188
eISSN - 1096-987X
pISSN - 0192-8651
DOI - 10.1002/(sici)1096-987x(20000115)21:1<52::aid-jcc6>3.0.co;2-7
Subject(s) - conical intersection , conical surface , ab initio , intersection (aeronautics) , point (geometry) , ethylene , oniom , computational chemistry , chemistry , configuration interaction , naphthalene , potential energy , atomic physics , physics , mathematics , geometry , engineering , molecule , organic chemistry , excited state , aerospace engineering , catalysis
An efficient procedure is presented for calculating analytic gradients in the framework of a semiempirical multireference configuration interaction method. The same algorithm is used to locate the lowest energy point of a conical intersection by the direct method of Bearpark et al. (Chem Phys Lett 1994, 223, 269). Results for the conical intersections on the photoreactions of ethylene and butadiene are in very good agreement with ab initio data. In addition, conical intersections were optimized of the photoreactions of azirine as well as for the cyclooctatetraen–semibullvalene and the dewarnaphthalene–naphthalene photorearrangement reactions. © 2000 John Wiley & Sons, Inc. J Comput Chem 21: 52–62, 2000