DETERMINATION OF THE ACTIVE SPACE IN MOLECULAR-DYNAMICS BY A TIME-DEPENDENT WAVE OPERATOR METHOD

The time-dependent wave operator formalism is used to describe the qua ntum dynamics of molecular systems. It is shown that the wave function , if correctly normalized at each moment of time, is the solution of a n ''instantaneous eigenvalue equation.'' This result is verified in th e case of an harmonic oscillator with a linear perturbation. It is fur ther shown that the resulting time-dependent ''eigenvalue'' can be use d to obtain the eigenvalues of the Floquet eigenvectors participating in the dynamics, and constituting the target space of the system. This is illustrated by a numerical example, concerning the photodissociati on of the H-2(+) ion in a continuous electromagnetic field. (C) 1997 A merican Institute of Physics.