A Time-dependent Quantum Dynamical Study Of H(D)+ HAu(DAu) Reaction

Molecular reaction dynamics is a chemical subject which studies reactions at the microscopic level,and people will understand more microscopic information about reactions,such as reactions mechanism.In recent years,molecular reaction kinetics has developed rapidly,and many scientific achievements have been obtained not only in experiment but also in theory.Among the theoretical calculation methods,the time-dependent wave packet method is particularly widely used,moreover the physical concept of the time-dependent wave packet method is simple and clear and the physical pictures are clear.The time-dependent wave packet method has both the visual pictures and quantum mechanical accuracy.The potential energy surface is the premise for kinetic calculations,so we should choose a concise potential energy surface before calculating.Our work is divided into the following three parts.We performed the time-dependent wave packet on H+HAu→Au+H₂/H+Au H reaction using the ground potential energy surface（2A’）constructed by Zanchet’et al.and Yuan PES and study isotope effect of this reaction on Yuan PES.For studying the mechanism of the title reaction,We calculated the following aspects about the H+HAu reaction.There is no threshold on the curves of the total probability and ICSs,because the reaction of the H+HAu→Au+H₂is a exothermic reaction.As the collision energy increases,the results of the reaction probability and ICSs are all increasing at frist then decreasing.For the reaction of the H+HAu→Au H+H,there is no threshold on the curves of the reaction probability and ICSs,and the trend of the curves are similar as the H+HAu→Au+H₂reaction.From the figure of the DCS,the direct mechanism is dominant in the H+HAu→Au+H₂reaction,while in the H+HAu→Au H+H reaction,the indirect mechanism is major.For H+HAu→Au+H₂reaction,the energy transfer goes essentially to vibration and rotation of H₂products.However,for H+HAu→Au H+H reaction,the collision energy is efficiently converted into rotational energy of the product,but not into vibrational energy efficiently.We also studied the same reaction on the Yuan potential energy surface.Because of the depth of the potential well which on the Yuan PES deeper than that on the Zanchet PES,the reaction probability and the value of the ICSs on the Yuan potential energy surface are smaller than the results from the Zanchet PES.In the low collision energy region,the values of the ICSs obtained from two PESs have more differences,which reflect that the depth of the potential well has a large effect on the values of the ICSs in the low collision energy region.It is also proved that small differences in the potential energy surface have a large effect on the dynamical results.On the DCSs and distribution curve of vibration and rotation,we get the same conclusion as H+HAu reaction on the Zanchet PES,which dominates that the difference in potential well depth and exotherm of the potential energy surface does not affect the reaction mechanism.We also studied of the dynamic characteristics of the D+DAu reaction with time-dependent wave packet on the Yuan potential energy surface.We find the isotopic effect has an effect on the reaction probability at low collision energy,but has little effect on the reaction probability at high collision energy.As the total angular momentum quantum number increases,the threshold of the H+HAu reaction increases faster than that of the D+DAu reaction because the centrifugal potential energy of the D+Au D system is less than that of the H+Au H system.The value of the ICSs for the D+DAu reaction is slightly lower than that H+HAu reaction.This may be due to the fact that the mass of the D atom are larger than that of the H atom,and more energy is needed for efficient collisions,from which we conclude that isotope effect reduces the reactivity slightly.On the DCSs and distribution curve of vibrationand rotation,we get the same conclusion as H+HAu reaction on the Yuan PES.