H-2 SCATTERING USING A NEW TIME-DEPENDENT METHOD FOR ELECTRON-NUCLEARDYNAMICS( +H, HE, AND H)

In this paper we apply the recently proposed and implemented electron nuclear dynamics (END) theory [J. Chem. Phys. 96, 6820 (1992)] to the study of prototypical ion-atom and ion-molecule collisions. The END th eory obtains the equations of motion from the time-dependent variation al principle (TDVP) employing a group theoretical coherent state (CS) parametrization of the wave function. The approach leads to a fully dy namical treatment of electrons and nuclei without invoking potential e nergy surfaces. The present implementation of the END theory constitut es the simplest ab initio model with the electrons described by a sing le determinantal wave function and the nuclei treated classically (or equivalently, with frozen Gaussian wave packets in the limit of a narr ow widths). The method is applied to the H+ + H, He, and H-2 collision processes in the energy range of 200-5000 eV. Results for the elastic and charge transfer differential cross sections, the differential pro babilities, and the rainbow angles are presented and compared with exp erimental data. Also, the dynamical trajectories, deflection functions , and differential vibrational excitation for the H-2 target are calcu lated and discussed. Effects of initial state molecular orientations, in the case of the H-2 target, are considered. In general, the results provided by this model implementation of the END theory are in good a greement with experimental data.