GENERALIZED MODELS OF NONADIABATIC TRANSITIONS

         L. Pichl$^\ast$, V. I. Osherov$^\sharp$ and H. Nakamura$^\ast$

  $^\ast$Institute of Molecular Science, Okazaki, Japan
  $^\sharp$Institute of Chemical Physics (Russian Academy of Sciences),
Moscow, Russia

Within the framework of the exponential model we developed an analytical
formula for nonadiabatic
transition matrix by means of semiclassical methods. The exponential
model can cover both basic
Landau-Zener-Stueckelberg (LZS) and Rozen-Zener-Demkov (RZD) type of
transitions. We introduce
general parameters for the transition matrix as contour integrals of
adiabatic momenta in the
coordinate plane. These (model-independent) quantities can be used for
more general potentials.