DENSITY-MATRIX DESCRIPTION OF ULTRAFAST DISSIPATIVE WAVE-PACKET DYNAMICS

Density matrix theory is applied to incorporate environmental effects and, thus, dephasing and relaxation into the description of vibrational wave packet dynamics on an ultrashort time scale. Instead of calculating the density matrix in the space of vibrational coordinates, the theory is formulated in vibrational eigenstates of appropriately chosen diabatic potential energy surfaces. Although a linear coupling between the vibrational degrees of freedom of the molecular system and those of the environment has been considered in detail, any type of coupling can be studied within the presented approach. The interplay of wave packet motion on the potential energy surfaces and energy dissipation into the environment is demonstrated for two simple one-dimensional examples.