Erik Deumens and Yngve Öhrn
We develop an approach to the time-dependent Schrödinger equation, which formulates the dynamics of molecular systems in terms of the central concept of a wavefunction phase space. A hierarchy of such Hilbert-space-based phase spaces is discussed. The dynamical equations, which approximate the Schrödinger equation and which determine the time evolution of the dynamical variables, are formulated using the time-dependent variational principle. This approach, which at its simplest level has been tested for a number of bimolecular reactive collisions of small systems is called electron nuclear dynamics (END). The structure of the theory and some results from its application are presented.