SEVEN-DIMENSIONAL QUANTUM DYNAMICS STUDY OF THEH2+NH2→H+NH3REACTION ON AN INTERPOLATED POTENTIAL ENERGY SURFACE

Abstract

Initial-state-selected time-dependent wave packet dynamics studies have been performed for the H2+ NH2→ H + NH3reaction with a seven-dimensional model on a new interpolated ab initio potential energy surface (PES). The PES is constructed using modified Shepard interpolation Scheme and contains 1967 data points with ab initio calculations carried out on UCCSD(T)/aug-cc-pVTZ level. In the seven-dimensional model, NH2group keeps C2vsymmetry and two NH bonds are fixed at their equilibrium values. The total reaction probabilities are calculated when (1) the two reactants are initially at their ground states; (2) NH2bending mode is excited, and (3) H2is on its first vibrational excited state. The integral cross sections are also reported for these initial states with centrifugal-sudden approximation. Thermal rate constants are calculated for the temperature range of 200–2000 K and compared with the previous calculated values and available experimental data. Good agreements between theory and experiments for the rate constants at intermediate temperature are achieved on this PES.