2-BY-2 DIABATIC APPROACH FOR MULTICHANNEL CURVE CROSSING PROBLEMS

A practically useful method is proposed to deaf with multi-channel cur ve crossing problems. This method deals with each crossing based on th e relevant two coupled diabatic states and provides a corresponding tr ansition matrix (I-matrix). The total reduced scattering matrix can be expressed by a product of these I-matrices. In this way, the present method can make full use of the advantages of the newly completed semi classical theory for two-state curve crossing problems, and can treat the multi-state curve crossing problems as simply as the two-state cas e. Some numerical demonstrations within a three-state model are presen ted.