Basics of surface hopping in mixed quantum/classical simulations

This paper gives an overview of mixed quantum/classical simulation techniques 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 addressed. First, the Ehrenfest approach, which relies on a single-configuration approximation to the total wave function, is explained. Then an analogous multi-configurational approach, to which surface hopping is an approximation, is given. The surface hopping method developed by John Tully is explained in detail. Several other methods are summarized and applications are discussed briefly to illustrate the scope of these methods. (C) 1999 Academic Press.