Abstract
The collision between hydrogen and ammonia is a benchmark system to study chemical elementary reactions with five atoms. In this work, we present a description of the system based on mixed Jacobi and Radau coordinates combined with the time-dependent wave packet method to study the H+NH 3 reaction. The Radau coordinates are used to describe the reactive moiety NH 2. A salient feature of this approach is that the present coordinates have the great advantage that a very small number of basis set functions can be used to describe the NH 2 group. Potential-optimized discrete variable representation basis is applied for the vibrational coordinates of the reagent NH 3. The reaction probabilities for several initial vibrational states are presented in this paper. The role of the different vibrational excitations on the reactivity is thoroughly described.