A SEMICLASSICAL APPROACH TO INTENSE-FIELD ABOVE-THRESHOLD DISSOCIATION IN THE LONG-WAVELENGTH LIMIT

A new semiclassical Formalism has been developed to treat Hamiltonians having explicit time dependence. with particular application to the d issociation of diatomic ions in intense laser fields. Based on this fo rmalism, a hopping algorithm is presented which specifies how classica l trajectories should be moved between coupled electronic surfaces. Th e theory is laid out in a rigorous, general form and an analysis is al so presented for tile case where only two electronic surfaces are stro ngly coupled. In addition, valuable physical insight into the hopping process is obtained by considering the theory in a number of physicall y relevant limiting cases. From this insight a number of guidelines ar e proposed which detail the manner in which trajectory hopping should be implemented when lime-dependent potential energy surfaces are prese nt, including the effects of phase coherence and conservation principl es. (C) 1996 American Institute of Physics.