Semiclassical estimation of Franck-Condon factors and transition rates for vertical and nonvertical transitions

Surface jumping is an intuitive concept. It gives a simple mechanistic picture of radiative or radiationless transitions between potential energy surfaces. According to this picture immediately after an electronic transition the nuclei are at a well defined region in phase space. This paper shows that when this simple picture applies, the transition rate can be calculated from the flow of probability from one potential energy surface to another at that phase-space region.