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Diabatic ordering of vibrational normal modes in reaction valley studies
Author(s) -
Konkoli Zoran,
Cremer Dieter,
Kraka Elfi
Publication year - 1997
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(19970730)18:10<1282::aid-jcc3>3.0.co;2-j
Subject(s) - diabatic , normal mode , degenerate energy levels , adiabatic process , chemistry , excited state , molecular vibration , normal coordinates , hot band , path (computing) , physics , molecular physics , molecule , atomic physics , quantum mechanics , vibration , computer science , programming language
Diabatic ordering of the normal model of a reaction complex alongthe reaction path has several advantages with regard to adiabatic ordering.The method is based on rotations of the vibrational normal modes at onepoint, s , of the reaction path to maximize overlap with thevibrational modes at a neighboring point. Global rotations precede therotations of degenerate modes so that changes in the direction of thereaction path and changes in the force constant matrix, which represent thetwo major effects for changes in mode ordering, can be separated. Overlapcriteria identify resolved and unresolved avoided crossings of normal modesof the same symmetry. Diabatic mode ordering (DMO) can be used to resolvethe latter by reducing the step size, thus guaranteeing correct ordering ofnormal modes in dependence of s . DMO is generally applicable toproperties of the reaction complex that depend on s such as normalmode frequencies, orbital energies, the energy of excited states, etc.Additional applications are possible using a generalized reaction pathvector, which may describe the change in atom masses, geometricalparameters, and/or the force constant matrix. In this way, the vibrationalspectra of isotopomers can be investigated or the vibrational frequenciesof different molecules correlated. © 1997 John Wiley & Sons,Inc. J Comput Chem 18: 1282–1294, 1997