INSTITUTO DE FISICA LA PLATA
Unidad Ejecutora - UE
congresos y reuniones científicas
Electronic Structure of α-Al2O3 Slabs: a local environment study
G.N. DARRIBA, R. FACCIO, AND M. RENTERÍA.
Workshop; FCM2010, International Workshop "At the Frontiers of Condensed Matter Physics V"; 2010
In this work we performed an ab initio/DFT study of structural and electronic propertiesof the (001) alpha-Al2O3 surface. For this study we used two methods with different basisset: the Augmented Plane Wave plus local orbital (APW+lo) and a linear combinationof numerical localized atomic orbital basis sets, employing the Wien2K code andSIESTA code, respectively. In order to calculate the structural and electronic propertiesof the reconstructed surface, we calculated the final equilibrium atomic positions withthe SIESTA code and then we calculated the Electric-Field Gradient (EFG) tensor withthe APW+lo code at the optimized positions.Using this procedure we found equilibrium structures with less energy than thoseobtained by using only the APW+lo method. The EFG tensor and the local structure for Al were study as a function of the depth from the surface, for relaxed structures. We found that distances down to 6 Å from the surface are sufficient to converge the EFG and the Al-O distances to bulk values. The predicted bulk EFG is in good agreement with the experimental results. These results can be used for local probe purposes, for example in the case of doping, with important sensitivity for probes located close to the top of the surface, in particular for distances lower than 6 Å.