A global potential energy surface and time-dependent quantum wave packet calculation of Au+H-2 reaction

A global potential energy surface (PES) corresponding to the ground state of AuH2 system has been constructed based on 22853 ab initio energies calculated by the multireference configuration interaction method with a Davidson correction. The neural network method is used to fit the PES, and the root mean square error is only 1.87 meV. The topographical features of the novel global PES are compared with previous PES which is constructed by Zanchet et al. (Zanchet PES). The global minimum energy reaction paths on the two PESs both have a well and a barrier. Relative to the Au+H-2 reactants, the energy of well is 0.316 eV on the new PES, which is 0.421 eV deeper than Zanchet PES. The calculation of Au(S-2)+H-2(X-1 sigma(+)(g)) AuH(X-1 sigma(+))+H(S-2) dynamical reaction is carried out on new PES, by the time-dependent quantum wave packet method (TDWP) with second order split operator. The reaction probabilities, integral cross-sections (ICSs) and differential cross-sections are obtained from the dynamics calculation. The threshold in the reaction is about 1.46 eV, which is 0.07 eV smaller than Zanchet PES due to the different endothermic energies on the two PESs. At low collision energy (<2.3 eV), the total ICS is larger than the result obtained on Zanchet PES, which can be attributed to the difference of the wells and endothermic energies