QUASI-AB INITIO DYNAMICS - A TEST TRAJECTORY STUDY OF THE H-2 REACTION USING ENERGIES AND GRADIENTS BASED ON SCALING OF THE EXTERNAL CORRELATION(H)

We have carried out a test dynamics study of the prototype H + H-2 exc hange reaction by running quasi-classical trajectories 'on-the-fly' us ing ab initio correlated energies which have been previously corrected semiempirically by the double many-body expansion plus scaling of the external correlation method to account for size-limitations of the on e-electron basis set and configuration interaction expansion. The meth od is general and gives results in agreement with conventional traject ory calculations carried out on the accurate double many-body expansio n potential energy surface for H,. (C) 1998 Elsevier Science B.V. All rights reserved.