AVS 58th Annual International Symposium and Exhibition
    Surface Science Division Monday Sessions
       Session SS2-MoA

Paper SS2-MoA10
Diffusion of Single Water and Hydrogen Sulfide Molecules on Ag(111): A DFT Study

Monday, October 31, 2011, 5:00 pm, Room 110

Session: Molecular Ordering and Electrochemical Interfaces
Presenter: Da-Jiang Liu, Ames Laboratory - US DOE
Correspondent: Click to Email
Diffusion of water (H2S) and hydrogen sulfide (H2S) on metal surfaces can be more complicated than single adatom diffusion, even for simple hopping mechanism. Additional degree of freedom, such as rotation and tilting of the molecule, must be considered. Due to the asymmetry of the molecule, and therefore the potential energy surface, the saddle points generally deviate from any high symmetry adsorption site. We carry out a systematic study based on the density-functional theory for diffusion of H2O and H2S on Ag(111). For both molecules, the most stable configuration for adsorption is nearly flat and on top of a Ag atom. As it approaches the bridge site, the molecule can tilt, and in the case of H2S, also rotate, to lower its energy. We also find that in this case, zero point vibrations contribute significantly to diffusion of the molecule.