Quantum dynamics simulations of energy redistribution in HO-SO2

Abstract Quantum dynamics simulations of HO–SO 2 using the coupled coherent state methodology are described in detail. Motivated by the assumption of fast intramolecular vibrational energy redistribution (IVR) within the nascent collision complex in measurements of the association rate coefficients using the ‘proxy’ method, we examine IVR within HO–SO 2 . Like our earlier classical dynamics calculations [D.R. Glowacki, S.K. Reed, M.J. Pilling, D.V. Shalashilin, E. Martinez-Nunez, Phys. Chem. Chem. Phys. 11 (2009) 963], the quantum dynamics results suggest that OH vibrational excitation is deactivated within HO–SO 2 prior to its dissociation, although the quantum IVR rates are greater than those in the classical simulations. The ubiquitous question of zero point energy in classical dynamics calculations is also considered. Reducing the quantity of zero point energy included in classical dynamics calculations decreases the HO–SO 2 dissociation rate and increases the deactivation of the OH stretch thereby producing vibrational energy distributions for the dissociated OH that more closely resemble those from the quantum dynamics calculations.

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