AVS 56th International Symposium & Exhibition
    Surface Science Tuesday Sessions
       Session SS1-TuM

Paper SS1-TuM12
Investigation of Oxygen Embedment and Surface Restructuring on the Cu(100) Surface by Density Functional Theory Calculations

Tuesday, November 10, 2009, 11:40 am, Room M

Session: Oxide Surfaces: Reactions and Structure
Presenter: M. Lee, Carnegie Mellon University
Authors: M. Lee, Carnegie Mellon University
A. McGaughey, Carnegie Mellon University
J. Ren, University of Pittsburgh
J.C. Yang, University of Pittsburgh
Correspondent: Click to Email
When the oxidation of a Cu(100) surface reaches 0.5 monolayer (ML) oxygen coverage, the surface structure transforms into the missing-row reconstruction. With further oxygen exposure, cuprite (Cu2O) islands nucleate and then grow both into and along the surface. To investigate the early stages of Cu(100) oxidation, we apply density functional theory calculations to study the oxygen embedment into the surface using the nudged elastic band (NEB) method. We find that as the surface oxygen coverage increases on the unreconstructed Cu(100) surface, the energy barrier for embedment decreases and the oxygen embedment is energetically favorable at coverages of 0.75 ML and 1.0 ML. At 0.5 ML coverage, the em- bedment energetics vary with surface morphology [c(2x2), missing-row reconstruction, and c(2x2) with 0.25 ML disordered vacancy structures], but in all cases the embedment is not energetically favorable. At 0.625 ML coverage, however, the oxygen embedment is favorable and we investigate the energetics for embedment into the missing row reconstruction through the missing row and alternate paths. We find that oxygen embedment through the missing row is more probable. We predict that oxygen sub-surface diffusion will occur because the energy barrier is comparable to that for surface diffusion. To study the intermediate states between the missing-row reconstruction and cuprite island nucleation, we are investigating various combinations of on- and sub-surface oxygen adsorbed structures by DFT calculation. We find that an additional oxygen molecule plays a role in the surface restructuring not only morphologically but also energetically for the unreconstructed Cu(100) surface. We are using a similar methodology to investigate the role of the additional oxygen molecule for surface restructuring on the missing-row reconstructed surface.