Localized Gaussian wave packet methods for inelastic collisions involving anharmonic oscillators

We examine several methods of implementing the time-dependent Gaussian wave packet method of Heller for collinear atom-molecule collisions involving anharmonic vibrators. We show that reasonably accurate results can be obtained with a procedure involving uncoupled frozen Gaussians with phases evaluated along classical trajectories. Although this method is much more accurate than the standard quasiclassical trajectory method, it involves about the same computational effort.