Aperiodic motion of nuclei and randomization in the electron-vibrational spectra of complex molecules

The electron-vibrational excitation correlator in a two-level molecule is obtained as a functional of the vibrational variables in a closed time contour. For deformational, optically active vibrations with frequency ω and a large Stokes shift ωΔ the values of the parameters model a number of molecules studied previously, possessing diffuse absorption and luminescence spectra. It is shown that the low-frequency vibrations near the separatrix of the phase plane of the deformation degree of freedom of the molecule resulting from their resonant nonlinear interaction μ with oscillations of the heat reservoir may be responsible for the smearing out of the spectral bands. The condition for the appearance of these almost aperiodic nuclear motions on the optical transitions is that the detuning Ω of the resonant vibrational exchange be small compared to the product μΔ