Transition state wave packet study of quantum molecular dynamics in complex systems

Abstract

Transition state time-dependent wave packet (TSWP) calculations have been carried out to study two prototype reactions. The first is the unimolecular dissociation of formaldehyde with nonreacting CO bond fixed. The cumulative reaction probability (J=0) and product state distributions were calculated to reveal two kinds of reaction pathways to H2+CO: the molecular channel and the roaming atom channel. The second reaction studied is H+CH4 to H2+CH3 reaction on the Jordan-Gilbert potential energy surface (JG-PES) with seven and eight dimensions included by restricting the CH3 group under C3V symmetry. The cumulative reaction probabilities (J=0) were calculated to give rate constants for temperature values between 200 and 500K employing J-shifting approximation. The second part of this work is test calculations with continuous-configuration time-dependent self-consistent field (CC-TDSCF) approach to study the flux-flux autocorrelation functions or thermal rate constants for three complex systems: H+CH4, hydrogen diffusion on Cu(100) surface, and the double well coupled to a dissipative bath. All these calculations revealed that the CC-TDSCF method is a very powerful approximate quantum dynamics method.