Basics of surface hopping in mixed quantum/classical simulations

This paper gives an overview of mixed quantum/classical simulation techniqu es based on the ideas of surface hopping (Tully, 1990). Basics such as the separation of a system into a classical and a quantum mechanical part are a ddressed. First, the Ehrenfest approach, which relies on a single-configura tion approximation to the total wave function, is explained. Then an analog ous multi-configurational approach, to which surface hopping is an approxim ation, is given. The surface hopping method developed by John Tully is expl ained in detail. Several other methods are summarized and applications are discussed briefly to illustrate the scope of these methods. (C) 1999 Academ ic Press.