Quantum dynamics from ab initio points

In this paper, we explore the numerical feasibility of carrying out quantum dynamics calculations from ab initio points for gas phase chemical reactions. In this approach, the ab initio data are first generated from quantum chemistry programs on a coarse numerical grid and a quantum dynamics calculation is then carried out using data from these grids. A crucial step in the success of this method is the application of a sequential one- dimensional fitting approach (SOFA) to give potential energy information off the original numerical grid. Using the SOFA scheme, one avoids the traditional and often intractable task of fitting a global potential energy surface from the ab initio data. In the present paper, a numerical test of this approach is reported for time-dependent wavepacket calculation for the prototype H + H₂ reaction.