Direct Subsurface Absorption of Hydrogen on Pd(111). Typeset Using Revt E X

We summarize and discuss some of the available experimental and theoretical data important for understanding the role played by subsurface sites in dissociative chemisorption calculations for the H2/Pd(111) system. Then we use a semi-empirical potential energy surface (PES) to model the interaction of a H2 molecule impinging on a Pd(111) surface. The London-Eyring-Polanyi-Sato (LEPS) construction has been extended to make direct subsurface absorption possible. A 2-dimensional wave packet calculation is used to find qualitative trends in the direct subsurface absorption and to reveal the time scales involved. We suggest that a partial in-plane relaxation occurs for the slowest incoming particles, thus resulting in a higher direct subsurface absorption probability for low energies. 68.35.Ja,82.20.Wt,82.20.Kh,82.65.Pa Typeset using REVTEX ∗Present address: Theoretische Chemie, Vrije Universiteit, De Boelelaan 1083, 1081 HV Amsterdam, The Netherlands