It is shown that the vibrational wave packet relaxation of initially cohere
nt (displaced) states as well as the quantum superposition of coherent stat
es in heat baths with different spectral densities exhibit a number of pecu
liarities compared with the cases of linear phase-sensitive relaxation, qua
dratic relaxation, and relaxational dynamics described with the use of Zure
k's environmentally induced pointer basis. A strong dependence of the relax
ation rate on the position of the spectral density maximum of the bath is f
ound. The differences can be used for the discrimination of the mechanisms
of the molecule-environment interactions. (C) 2001 Elsevier Science B.V. Al
l rights reserved.