Multiconfiguration time-dependent Hartree method applied to molecular dissociation on surfaces:H_2+Pt(111)

摘要

Four-dimensional quantum dynamics calculations are performed on the dissociative chemisorption of H_2 on Pt(111) using the multiconfiguration time-dependent Hartree method.The aim of this work is to study the performance of the multiconfiguration time-dependent Hartree method for a gas-surface reaction by comparison with the standard time-dependent wave-packet propagation method.The initial-state resolved dissociation probability of H_2 is calculated within two four-dimensional models.The first four-dimensional model treats explicitly the rotational motion of the molecule and the H_2 dissociation is studied above two different sites of the Pt(111).For this model,only a potential-energy surface of general form was available.This potential was refitted to a sum of product form to allow efficient calculations with the multiconfiguration time-dependent Hartree method.The second model focuses on the description of the center-of-mass motion parallel to the surface,the rotational motion of the molecule being frozen.These four-dimensional quantum dynamics calculations yield important insights which can help with performing full six-dimensional calculations on H_2 dissociating on Pt(111).The multiconfiguration time-dependent Hartree method is shown to be particularly efficient for computing initial-state selective dissociation probabilities for the system studied,with a good accuracy and a reduced amount of memory and computational time when compared to the standard time-dependent wave-packet method.