Reaction cross sections for the H + D_2(#nu# = 0, 1) system for collision energies up to 2.5 eV: A multiconfiguration time-dependent Hartree wave-packet propagation study

摘要

Cumulative initial-state-selected cross sections for the H+D_2(#nu#, j) -> HD + D reaction are presented. Initial states with vibrational quantum numbers #nu# = 0, 1 and rotational quantum numbers j=0-4, and initial translational energies up to 2.5 eV are considered. These calculations go beyond previous ones in treating higher energies and vibrationally excited D_2. The cross sections are computed by propagating wave packets employing the multiconfiguration time-dependent Hartee scheme, and by analyzing the reactive flux into the configuration channel of the products. The initial wave packets are modified to account for the long-range part of the potential, assuming vibrational adiabaticity. All calculations are performed within the coupled states approximation on the Liu-Siegbahn-Truhlar-Horowitz (LSTH) potential-energy surface. The LSTH surface is expanded in products of one-dimensional functions of the Jacobian coordinates. The initial-state-selected cross sections are averaged over a room-temperature Boltzmann distribution of the D_2 rotational states to compare the results with experimentally observed values. The relative efficiency of vibrational, rotational, and translational energy for promoting the reaction is analyzed.