Speaker: Dr. SHEN Xiangjian
Date and Time: 15:00-17:00pm, September 21, 2017
Venue: Meeting Room 223, IPE Building
Title: Dynamics of Methane Dissociation on Ni Surfaces and Atomic Hydrogen Diffusion on Model Catalysts Surfaces
Gas-surface interaction is a very important branch in the field of surface chemical reaction dynamics. First, we present some dynamics results about the role of molecular degrees of freedom(DOFs) of CH4dissociation on Nickel surfaces from seven-dimensional to nine di-mensionalquantum models. It is quantitatively found that, the DOF of stretching CH limitedin C3v symmetry weakly enhances the final sticking probability S0; the DOF of azimuth strongly weakens the final S0; two lateral DOFs of surface impact sites largely decrease the final S0; and the DOF of lattice thermal motion strongly increases the final S0. These importantroles of reaction coordinates clearly show the complex but interesting surface reactiondynamics features in polyatomic gas-surface reactions. Second, combining of the cubic spline interpolation approach and abinitiodensity functional theory(DFT), we present some global and clear pictures of atomic hydrogen diffusion pathways on and into model metal catalysts (100) and (111) surfaces, such as Fe, Ni, Pd et al. In comparison with hydrogenforward diffusion pathway and its inversion, the high reactivity of subsurface hydrogenis mainly contributed from the residual energy emerging from subsurface onto surface. Two different diffusion mechanisms are given. Our results not only reproduce the pathways determined from DFT calculations, but also provide more diffusion details in the complex subsurface regions.