Title

Friedel oscillations responsible for stacking fault of adatoms: The case of Mg(0001) and Be(0001)

Authors

Authors

M. A. Ortigoza; M. Aminpour;T. S. Rahman

Comments

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Abbreviated Journal Title

Phys. Rev. B

Keywords

MULTILAYER RELAXATIONS; 0001 SURFACE; MG; Physics, Condensed Matter

Abstract

We perform a first-principles study of Mg adatom/adislands on the Mg(0001) surface, and Be adatom on Be(0001), to obtain further insight into the previously reported energetic preference of the fcc faulty stacking of Mg monomers on Mg(0001). We first provide a viewpoint on how Friedel oscillations influence ionic relaxation on these surfaces. Our three-dimensional charge-density analysis demonstrates that Friedel oscillations have maxima which are more spatially localized than what one-dimensional average density or two-dimensional cross-sectional plots could possibly inform: The well-known charge-density enhancement around the topmost surface layer of Mg(0001) is strongly localized at its fcc hollow sites. The charge accumulation at this site explains the energetically preferred stacking fault of the Mg monomer, dimer, and trimer. Yet, larger islands prefer the normal hcp stacking. Surprisingly, the mechanism by which the fcc site becomes energetically more favorable is not that of enhancing the surface-adatom bonds but rather those between surface atoms. To confirm our conclusions, we analyze the stacking of a Be adatom on Be(0001)-a surface also largely influenced by Friedel oscillations. We find, in fact, a much stronger effect: The charge enhancement at the fcc site is even larger and, consequently, the stacking-fault energy favoring the fcc site is quite large-44 meV.

Journal Title

Physical Review B

Volume

91

Issue/Number

11

Publication Date

1-1-2015

Document Type

Article

Language

English

First Page

9

WOS Identifier

WOS:000350995400008

ISSN

1098-0121

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