Theoretical studies of the potential energy surface and wavepacket dynamics of the Li3 system

The three-dimensional (3D) potential energy surface of the ground state of Li₃ was determined by the multireference configuration interaction method. The vibrational motions and pseudorotation were investigated by a 3D time-dependent wavepacket formalism. The analytical expression of the 3D surface is given and the results of vibrational analyses at several critical points are presented. The low-lying excited states of Li₃ were examined for the C _{2 v} structure and the vertical and adiabatic excitation energies were calculated. The ground and singlet excited states of Li₂ were calculated and their spectroscopic constants compare well with the experimental values. A 3D wavepacket calculation was performed for simulations of the stimulated emission pumping spectrum in which the A state was taken as an intermediate. The recurrences of the autocorrelation functions were characterized by classical trajectory calculations. The autocorrelation functions obtained by wavepacket propagation are reproduced well by the accumulation of the classical trajectories in the short-time region. Received: 2 July 1998 / Accepted: 3 September 1998 / Published online: 8 February 1999