Nitrogen adsorption and thin surface nitrides on Cu(1 1 1) from first-principles |
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Authors: | Aloysius Soon Lindee Wong Mira Todorova Bernard Delley |
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Institution: | a School of Physics, The University of Sydney, Sydney, New South Wales 2006, Australia b Paul-Scherrer-Institut, CH-5232, Villigen PSI, Switzerland |
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Abstract: | Experimental studies of nitrogen adsorbed on a Cu(1 1 1) surface show that the surface layer undergoes a reconstruction to form a pseudo-(1 0 0) structure. We use ab initio techniques to demonstrate the theoretical stability of this reconstructed surface phase over a range of conditions. We systematically investigate the chemisorption of N on the Cu(1 1 1) surface, from 0.06 to 1 ML coverage. A peculiar atomic relaxation of N atoms for 0.75 ML is identified, which results in the formation of a (metastable) “N-trimer cluster” on the surface. We have also investigated surface nitride formation, as suggested from experiments. A surface nitride-like structure similar to the reported pseudo-(1 0 0) reconstruction is found to be highly energetically favored. Using concepts from “ab initio atomistic thermodynamics”, we predict that this surface nitride exists for a narrow range of nitrogen chemical potential before the formation of bulk Cu3N. |
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Keywords: | Density functional calculations Nitridation Surface structure Morphology Copper Nitrogen Surface thermodynamics Surface nitrides |
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