Semiclassical Motion of Systems with Internal States

In many fields of atomic and molecular physics we need to combine the center-of-mass motion with internal degrees of freedom. In this work, the classical motion in phase space is separated from the quantum processes by a multiple-time-scale approach. The expansion parameter is proportional to Planck's constant. The theory is given and illustrated by examples: the semiclassical description of a particle without internal states, the extraction of a classical trajectory and the derivation of the light-induced force.