Eight-Dimensional Quantum Dynamics Study of CH4 and CD4 Dissociation on Ni(100) Surface

Methane dissociation on Ni(100) surface is one of the benchmark systems for exploring polyatomic molecular gas–surface reaction dynamics. We here present an eight-dimensional quantum dynamics study based on developing a highly accurate, 15-dimensional potential energy surface(PES). The CH4 interacting on a rigid Ni(100) surface is described with the methodology of neural network (NN) fit to plenty of ab initio configuration-energy points. With the best-fitting NN(PES), we obtain the sticking probability S0 of ground state (GS) CH4 and its isotopologue CD4 on a rigid Ni(100) from some direct quantum dynamics simulations. The promising azimuth-averaged and site-averaged approaches are employed to treat the influence of surface impact sites. The improved nonlinear lattice-sudden model is considered for the surface temperature effect. The final S0 of GS CH4 on Ni(100) surface at 475 K is in excellent agreement with two sets of available experiments. Furthermore, we calculate the S0 of GS CD4 on Ni(100) surface at 475 K. It is much lower than that GS CH4, which mainly contributes from the zero-point vibrational energy difference.