APPROXIMATELY DIABATIC STATES - A RELATION BETWEEN EFFECTIVE HAMILTONIAN TECHNIQUES AND EXPLICIT CANCELLATION OF THE DERIVATIVE COUPLING

The identification of specific electronic structures that do not interchange with varying geometry is related to the problem of finding a set of approximately diabatic states. We propose a new transformation to identify such structures from one nuclear configuration to another one. This transformation, used in previously proposed schemes to construct nearly diabatic states, improves the efficiency of these procedures which can be related to the methods minimizing explicitly the nonadiabatic coupling. © 1990 American Institute of Physics.