A test of the continuous configuration time-dependent self-consistent field (CC-TDSCF) method on the H + CH4 reaction.

The continuous configuration time-dependent self-consistent field (CC-TDSCF) method is employed to calculate the flux-flux autocorrelation functions for the H + CH4 reaction on the potential energy surface recently developed by Manthe and co-workers. We include up to 10 out of the total 12 degrees of freedom in our calculations, only with the doubly degenerate bending modes involving the motion of the hydrogens in nonreacting CH3 group excluded. Comparison of flux-flux autocorrelation functions obtained by using the exact dynamics method and the CC-TDSCF method shows that the CC-TDSCF method is capable of producing very accurate results. Our calculations clearly reveal that the CC-TDSCF method is a powerful approximation quantum dynamics method. It allows us to partition a big problem into several smaller ones. By changing partition systematically, one can investigate the correlations between different degrees of freedom. By grouping modes with strong correlations together as a cluster, one can systematically improve accuracy of the result.