EFFECT OF NONADIABATICITY ON THE VIBRONIC SPECTRA OF MOLECULES.

The adiabatic approximation is one of the most important approximations in the theory of vibronic spectra of molecules. To estimate the nonadiabatic effect frequently such calculations, especially calculations of transition intensities in large polyatomic molecules, lead to a distorted picture of the energy distribution in the spectrum of the molecule; this might be related to a shortcoming of the adiabatic model, which does not take into account the effect of the nonadiabatic mixing of different vibronic states. We developed a set of FORTRAN programs which make it possible to use the variation method to calculate the energy of vibronic transitions in the nonadiabatic approximation, and also the nonadiabatic mixing of the wave functions of adiabatic vibronic states.