Mode specificity of the dissociative chemisorption of HOD on rigid Cu(111): an approximate full-dimensional quantum dynamics study

The validity of the site averaging approximation with exact potential (SAEP) has been confirmed in a recent work on the H2O/Cu(111) system Z. Zhang, T. Liu, B. Fu, X. Yang, D. H. Zhang, Nat. Commun. 2016, 7, 11953. Here, the mode specificity of the dissociative chemisorption of HOD on a rigid Cu(111) surface is investigated by carrying out the seven-dimensional (7D) quantum dynamics calculations on an accurate nine-dimensional (9D) potential energy surface together with the implementation of the SAEP. The approximate 9D dissociation probabilities for HOD initially in various vibrational states are obtained by averaging the site-specific 7D results over 9 impact sites. A strong bond-selective effect for the title reaction is observed, where vibrational excitation of a particular bond leads to a large enhancement only in the reaction in which the excited bond is broken. The product branching ratios strongly depend on which bond is excited, and the product from the cleavage of the excited bond is much more favored than the other product. The implementation of the SAEP allows us to investigate the mode-specific dynamics at a level of accuracy that can only be achieved in full-dimensional quantum dynamics calculations.