Dresden 2006 – wissenschaftliches Programm

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O: Oberflächenphysik

O 46: Adsorption VI

O 46.6: Vortrag

Freitag, 31. März 2006, 12:30–12:45, TRE Phys

An ab initio Study of Topographical Defects on NaCl(100) — •Bo Li, Angelos Michaelides, and Matthias Scheffler — Fritz-Haber-Institut der Max-Planck-Gesellschaft Faradayweg 4-6, D-14195 Berlin, Germany

Ab initio calculations based on density-functional theory (DFT) within the plane-wave pseudopotential formalism have been performed for a wide variety of defects on NaCl surfaces. Specifically, Na and Cl vacancies and adatoms as well as neutral and polar steps have been examined.

These DFT calculations have yielded several interesting results, such as the first ab initio determinations of the surface energy of NaCl(100) and monatomic step formation energies. In addition, it is found that Cl adatoms exhibit a preference for adsorption on top of Cl substrate sites, rather than above Na substrate sites as might be anticipated. A series of second order Møller-Plesset perturbation theory (MP2) calculations for Cl adatoms on small NaCl clusters show the same binding site preference, thus lending support to this “non-textbook” result. The explanantion for this unusual result is, however, perfectly textbook: a weak covalent bond that forms only when Cl adatoms reside above Cl substrate atoms.