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Modeling of vibronic interaction and chaotic dynamics in electronic and nuclear subsystems of molecules
Author(s) -
Morozov V. A.,
Dubina Y. M.
Publication year - 2002
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.10208
Subject(s) - physics , excitation , vibronic coupling , excited state , quantum , harmonic oscillator , quantum mechanics , adiabatic process , quantum dynamics , molecule , population , coupling (piping) , atomic physics , demography , sociology , mechanical engineering , engineering
The interaction of electronic and nuclear subsystems of a molecular system is described to be a consequence of cubic and biquadratic coupling on coordinates between electronic and nuclear oscillators in the classic and mixed quantum–classic models of a molecule. The simple relationships between two parameters of nonlinearity and usually used in the description of adiabatic vibronic interaction in a real molecules a shift of equilibrium position of nuclei and change of force constant them harmonic vibrations upon electronic excitation of a molecule are established. It is shown that performance of these relationships averaged on “fast” time dynamics of excitation of electronic oscillators of the classic model coincides with dynamics of population of the excited electronic state of the mixed quantum–classic model for any values of nuclear positions. The influence considered vibronic interaction on the character of dependence of quasienergies of a molecule dressed by a cloud of photons from the coordinate nuclear oscillator is investigated. As a necessary condition for the appearance of chaotic dynamics of nuclei in the considered quantum–classic model of a molecule at transformation by its light fields it is proposed to consider the occurrence of two‐well quasienergy. Taking account this criterion, it is shown that only the considered cubic (but not biquadratic) vibronic interaction is one of the reasons for the chaotic dynamics of nuclei in molecules interacting with a light field. © 2002 Wiley Periodicals, Inc. Int J Quantum Chem, 2002