INVESTIGADORES
RENTERIA Mario
congresos y reuniones científicas
Título:
FP-LAPW Study of Pure and Cd-Dopped Indium Metallic Surfaces
Autor/es:
L.A. ERRICO; M. WEISSMANN; M. RENTERÍA
Lugar:
Pucón
Reunión:
Conferencia; XI Latin American Congress of Surface Science and its Applications; 2003
Institución organizadora:
Universidad de Chile
Resumen:
Structural and
electronic properties at and near surfaces are important to understand the
interaction of atoms under these special boundary conditions. In particular,
the reconstructions and surface states
are being studied for both basic and technological reasons. For example,
changes of the electronic properties between different atomic layers (or even
between atoms in the same layer) are of fundamental interest.
One way to obtain
electronic properties on an atomic scale is offered by hyperfine experimental
techniques. In particular, g-g Perturbed-Angular
Correlations (PAC) provides a high resolution determination of the electric-
field-gradient (EFG) tensor at the site of a probe-atom, a magnitude
particularly sensitive to slight local changes in the electronic charge density
around the probe. With this technique, monolayer-resolved studies are possible
[1]. The measured EFG could give structural and electronic information of the
system that cannot be obtained by other methods, but their interpretation is
not straightforward. All-electron ab-initio calculations, based on
density functional theory, have been successfully used by us as a complementary
tool for the investigation of the EFG at impurities in oxides [2-4].
The purpose of
this communication is to present a first-principles study of the electronic and
structural properties of pure and Cd-dopped Indium metallic surfaces. The EFG
at the Cd impurity replacing an Indium atom of the bulk and of the surface
are also calculated in order to validate
the theoretical results by means of the comparison with 111Cd PAC
experimental results.
The study was
performed with the WIEN97
implementation, developed by Blaha et al. [5], of the full-potential
linearized-augmented-plane-wave (FP-LAPW) method. It considers no shape
approximation on either the potential or the electronic charge density, being
thus specially suited for EFG calculations. In order to approximate the
dilution of the Cd impurity we used supercells of increasing size, all
containing a single Cd atom, and calculated the self-consistent potential and
charge density inside each one. We studied the relaxation introduced by the
impurity by computing the forces on the Cd neighbors and moving them until the
forces vanished. For the surface cases we studied first the reconstruction of
the pure In metal surfaces and then study the effect of replacing one In atom
by a Cd impurity. Finally, we compare the results with the experimental PAC
data [1].
This research was
partially supported by Fundación Antorchas, ANPCyT (PICT 03-03727), CONICET, Argentina, and TWAS, Italy.
References
[1] W. Körner, W. Keppner, B. Lehndorff-Junges,
and G. Schatz, Phys. Rev. Lett. 49, 1735 (1982).
[2] L. A. Errico, G.
Fabricius, and M. Rentería, Hyperfine Interac. 136/137, 749 (2001).
[3] L. A. Errico, G.
Fabricius, M. Rentería, P. de la Presa, and M. Forker, Phys. Rev. Lett. 89, 55503 (2002).
[4] L. A. Errico, G. Fabricius, and M.
Rentería, Phys. Rev. B 67, 144104
(2003).
[5] P. Blaha, K. Schwarz, P. Dufek, and J. Luitz, Wien97, (K. Schwarz,
Technische Universtität Wien, Austria, 1999), ISBN 3-9501031-0-4.