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T. Franz, J. Zabloudil, F. Mittendorfer, L. Gragnaniello, G. Parteder, F. Allegretti, S. Surnev, F. Netzer:
"Deformed Surface Oxides: Uncommon Sturcture of a (6x1) NiO Surface Oxide on Rh(111)";
Journal of Physical Chemistry Letters, 3 (2012), 186 - 190.

We have investigated the formation of a nickel oxide monolayer on
Rh(111) by scanning tunneling microscopy (STM), high-resolution electron energy loss
spectroscopy (HREELS), and density functional theory (DFT) calculations. This
monolayer displays a corrugated (6 × 1) superstructure, with a formal Ni5O5
stoichiometry. The interplay between polarity and interface energy leads to the formation
of a structure with pronounced troughs, which may be regarded as a building deformation,
containing building blocks derived from nonpolar (100) and polar (111) NiO surface
terminations. The calculations also show that the (6 × 1) Ni5O5 phase has a higher
thermodynamic stability than the related octopolar NiO bulk terminations.