Article (Scientific journals)
Nonadiabatic Unimolecular Reactions of Polyatomic Molecules
Desouter-Lecomte, Michèle; Dehareng, Dominique; Leyh-Nihant, Brigitte et al.
1985In Journal of Physical Chemistry, 89, p. 214-222
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Keywords :
nonadiabatic coupling; avoided crossing; conical intersection; Jahn-Teller intersection; Renner-Teller interaction
Abstract :
[en] The nonadiabatic couplings which arise when two potential energy surfaces of a polyatomic molecule get close in energy can be classified as follows: (A) avoided crossings, (B) genuine intersections (Jahn-Teller and conical), (C) glancing intersections (Renner-Teller interactions). The characteristics of the potential energy surfaces in the adiabatic and diabatic representations are discussed for each case. The three coupling cases differ in the structure of the Hamiltonian matrix. When the latter is written in the diabatic representation, it is meaningful to retain the leading term only in its power series expansion. This gives rise to a so-called minimum-order model which is found to be surprisingly accurate (at least in a restricted zone of nuclear coordinates) when compared to the results of ab initio calculations. The characteristic features of each coupling case can only be understood in a two-dimensional configuration space, Le., when two nuclear degrees of freedom, often with different symmetry properties, are explicitly considered. A simple expression of the nonadiabatic transition probability between two electronic states can be worked out in the framework of the minimum-order models. Two-dimensional extensions of the Landau-Zener formula are obtained, which can be used to study the consequences of the anisotropic properties of the coupling. In the case of avoided crossings, only nuclear trajectories having a well-defined direction are able to bring about surface hopping, wheras there exists two active degrees of freedom for conical intersections. Hence, nonadiabatic processes which are controlled by genuine intersections are expected to take place faster than those controlled by avoided crossings.
Disciplines :
Chemistry
Author, co-author :
Desouter-Lecomte, Michèle ;  Université de Liège - ULiège > Département de chimie (sciences) > Laboratoire de chimie physique théorique
Dehareng, Dominique ;  Université de Liège - ULiège > Centre d'ingénierie des protéines
Leyh-Nihant, Brigitte
Praet, Marie-Thérèse
Lorquet, Andrée ;  Université de Liège - ULiège > Département de chimie (sciences) > Laboratoire de dynamique moléculaire
Lorquet, Jean-Claude ;  Université de Liège - ULiège > Services généraux (Faculté des sciences) > Relations académiques et scientifiques (Sciences)
Language :
English
Title :
Nonadiabatic Unimolecular Reactions of Polyatomic Molecules
Publication date :
1985
Journal title :
Journal of Physical Chemistry
ISSN :
0022-3654
eISSN :
1541-5740
Publisher :
American Chemical Society, Washington, United States - District of Columbia
Volume :
89
Pages :
214-222
Peer reviewed :
Peer Reviewed verified by ORBi
Funders :
FRIA - Fonds pour la Formation à la Recherche dans l'Industrie et dans l'Agriculture [BE]
FRFC - Fonds de la Recherche Fondamentale Collective [BE]
BELSPO - SPP Politique scientifique - Service Public Fédéral de Programmation Politique scientifique
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