REACTANT-PRODUCT DECOUPLING METHOD FOR STATE-TO-STATE REACTIVE SCATTERING - A CASE-STUDY FOR 3D H-2 EXCHANGE-REACTION (J=0)(H)

In this paper, we present theoretical and computational details of imp lementing the recently developed reactant-product decoupling (RPD) met hod (J. Chem. Phys. 105, 6072 (1996)) for state-to-state quantum react ive scattering calculations of the prototypical H + H-2 reaction in th ree dimensions. The main purpose of this paper is to explore important features of the RPD scheme for use as a general and efficient computa tional approach to study state-to-state quantum dynamics for polyatomi c reactions by using 3D H + H-2 as an example. Specific computational techniques and numerical details are explicitly provided for efficient application of this method in the time-dependent (TD) implementation. Using the RPD method, the calculated state-to-state reaction probabil ities for the 3D H + H-2 reaction are in excellent agreement with thos e from the time-independent variational calculations, and the computat ional cost of the RPD method is significantly lower than other existin g TD methods for state-to-state dynamics calculations. (C) 1997 Americ an Institute of Physics.