B. Hammer

Publications (4)0 Total impact

• Source

  Available from: Peter Kratzer

  Article: A direct pathway for sticking/desorption of H$_2$ on Si(100)

  P. Kratzer, B. Hammer, J. K. Norskov
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  ABSTRACT: The energetics of H$_2$ interacting with the Si(100) surface is studied by means of {\em ab initio} total energy calculations within the framework of density functional theory. We find a direct desorption pathway from the mono-hydride phase which is compatible with experimental activation energies and demonstrate the importance of substrate relaxation for this process. Both the transition state configuration and barrier height depend crucially on the degree of buckling of the Si dimers on the Si(100) surface. The adsorption barrier height on the clean surface is governed by the buckling via its influence on the surface electronic structure. We discuss the consequences of this coupling for adsorption experiments and the relation between adsorption and desorption. Comment: 18 pages + 8 figures
  03/1995;
• Source

  Available from: mpg.de

  Article: The CO/Pt(111) puzzle

  P. J. Feibelman, B. Hammer, J. K. Norskov, F. Wagner, Matthias Scheffler, Roland Stumpf, R. Watwe, J. Dumesic
  Journal of Physical Chemistry B, v.105, 4018-4025 (2001).
• Article: Theoretical surface science and catalysis—calculations and concepts

  B. Hammer, J.K. Nørskov
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  ABSTRACT: The application of density functional theory to calculate adsorption properties, reaction pathways, and activation energies for surface chemical reactions is reviewed. Particular emphasis is placed on developing concepts that can be used to understand and predict variations in reactivity from one transition metal to the next or the effects of alloying, surface structure, and adsorbate-adsorbate interactions on the reactivity. Most examples discussed are concerned with the catalytic properties of transition metal surfaces, but it is shown that the calculational approach and the concepts developed to understand trends in reactivity for metals can also be used for sulfide and oxide catalysts.
  Advances in Catalysis.
• Article: The coupling between adsorption dynamics and the surface structure: H2 on Si(100)

  P. Kratzer, B. Hammer, J.K. Nørskov
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  ABSTRACT: We provide direct theoretical evidence for the existence of a strong coupling between the barrier for H2 dissociation and the structure of the Si(100) surface. Our arguments are based on an ab initio calculation of the potential energy surface for the dissociation process. While adsorption on the buckled dimers, which make up the surface ground state, is found to be activated by 0.67 eV, exciting the dimers to a less buckled configuration lowers the barrier considerably. We argue that such a coupling is the key to resolve the apparent inconsistencies between desorption and sticking experiments and present a model calculation of its consequences for the variation of the adsorption probability with surface temperature. We can account quantitatively for the recently observed thermally activated sticking of H2 on this surface.
  Chemical Physics Letters.