Dynamics of H + +CO at E Lab =30 eV

Abstract

The astrophysically relevant system H CO (v i 0) → H CO (v f) at E Lab 30 eV is studied with the simplest-level electron nuclear dynamics (SLEND) method. This investigation follows previous successful SLEND studies of H H 2 and H N 2 at E Lab 30 eV J. Morales, A. Diz, E. Deumens, and Y. hrn, J. Chem. Phys. 103(23), 9968 (1995)10.1063/1.469886; C. Stopera, B. Maiti, T. V. Grimes, P. M. McLaurin, and J. A. Morales, J. Chem. Phys. 134(22), 224308 (2011)10.1063/1. 3598511. SLEND is a direct, time-dependent, variational, and non-adiabatic method that adopts a classical-mechanics description for the nuclei and a single-determinantal wavefunction for the electrons. A canonical coherent-states (CS) procedure associated with SLEND reconstructs quantum vibrational properties from the SLEND classical dynamics. Present SLEND results include reactivity predictions, snapshots of the electron density evolution, average vibrational energy transfers, rainbow angle predictions, total and vibrationally resolved differential cross sections (DCS), and average vibrational excitation probabilities. SLEND results are compared with available data from experiments and vibrational close-coupling rotational infinite-order sudden (VCC-RIOS) approximation calculations. Present simulations employ four basis sets: STO-3G, 6-31G, 6-31G, and cc-pVDZ to determine their effect on the results. SLEND simulations predict non-charge-transfer scattering and CO collision-induced dissociation as the main reactions. SLEND6-31G, 6-31G, and cc-pVDZ predict rainbow angles and total DCS in excellent agreement with experiments and more accurate than their VCC-RIOS counterparts. SLEND6-31G and cc-pVDZ predict vibrationally resolved DCS for v f 0-2 in satisfactory experimental agreement, but less accurate than their comparable H CO VCC-RIOS and H H 2 and H N 2 SLEND results. SLEND6-31G and cc-pVDZ predict qualitatively correct average vibrational excitation probabilities, which are quantitatively correct for v f 2, but under(over)estimated for v f 0(1). Discrepancies in some H CO SLEND vibrational properties, not observed in H H 2 and H N 2 SLEND results, are attributed to the moderately overestimated SLEND vibrational energy through its effect upon the canonical CS probabilities. Correction of that energy to its experimental values produces a remarkable improvement in the average vibrational excitation probabilities. Ways to obtain more accurate vibrational properties with higher-level versions of electron nuclear dynamics are discussed. © 2012 American Institute of Physics.