INSTITUTO DE FISICA LA PLATA
Unidad Ejecutora - UE
congresos y reuniones científicas
Cd impurities in (001) α-Al2O3 Slabs
GERMÁN NICOLÁS DARRIBA; RICARDO FACCIO; MARIO RENTERÍA
Workshop; V Workshop on Novel Methods for Electronic Structure Calculations; 2013
Universidad de la República
In this work we performed an ab initio/DFT study of structural and electronic properties of Cd impurities in the (001) alpha-Al2O3 surface. The Cd impurities were placed at the different Al substitutional sites as a function of the depth from the surface. For this study we used two methods with different basis set: Full-Potential the Augmented Plane Wave plus local orbital (FP-APW+lo) and a linear combination of numerical localized atomic orbital basis sets, employing the WIEN2k code and the SIESTA code, respectively. In order to reconstruct the surface, we calculated in each case the equilibrium atomic positions with the SIESTA code and then we calculated the Electric-Field Gradient (EFG) tensor with the APW+lo code at the optimized positions. In the last case, a little refinement of the structure was necessary in order to found the final equilibrium positions. Using this procedure we found equilibrium structures with less energy than those obtained by using only the APW+lo, and has already been demonstrated successful in the case of pure alpha-Al2O3 slabs . The EFG tensor and the local structure at Cd sites were studied as a function of the depth from the surface, for relaxed structures. We found that is necessary that Cd atom is placed deeper than the indigenous Al atom in pure Al2O3 for converge the EFG and the Cd-O distances to bulk values.  G. N. Darriba, R. Faccio, and M. Rentería, Physica B 407, 3093 (2012).