Time-dependent wave packet study of the N++H-2 reaction

The time-dependent wave packet method has been used to calculate initial st ate selected reaction probabilities, reaction cross sections, and rate cons tants for the N+ + H-2 reaction on the potential energy surface of Wilhelms son, Siegbahn, and Schinke [J. Chem. Phys. 96, 8202 (1992)]. In addition to providing results that can be used to test more approximate theories, thes e calculations are used to shed light on a number of key issues concerning the reaction, including the correct value of the reaction endothermicity, t he reactivity of excited H-2 rotational states, and the lifetimes of the in termediate NH2+ complexes that are formed in collisions of N+ with H-2(upsi lon = 0) and H2(upsilon = 1) We also show that an earlier quasiclassical tr ajectory study of the reaction on the same potential energy surface predict ed the wrong cross-section behavior in the threshold region as a result of an incorrect treatment of product zero-point energy. (C) 1999 American Inst itute of Physics. [S0021-9606(99)00601-7].