DFT study of the adsorption of Ni on Anatase (001) surface

Potential energy curves and different adsorption sites of Ni on Anatase (001) surface, at increasing coverage, were computed at singlet, triplet, and quintuplet multiplicity states. Coverage was increased until a complete adlayer is reached. A density functional theory (DFT based method (periodic D Mol(3) included in MS package) was used. At the lowest coverage of our system (one Ni per 2 x 2 x 1 unit cells) different adsorption sites were found at the holes on the surface. At the triplet multiplicity state, two deep minima were found at 0.55 and 0.11 angstrom from the bridging oxygen plane (BOP) on the surface with adsorption energies of 3.5 and 3.74 eV, respectively. Both of these minima showed spin transfer from the Ni to the Ti atoms at the relaxed slab surfaces. With singlet multiplicity a BOP minimum was found at -0.33 angstrom. For high coverages, spin multiplicity of the system turned out to be the singlet. This shows similar trends alike in the clustering of Ni on Anatase (001) surface. Calculated surface energy decreased until full coverage, and the surface energy per Ni also decreased up to saturation value at full coverage. (C) 2011 Elsevier B.V. All rights reserved.