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Title: | Ground- and excited-state properties of M-center oxygen vacancy aggregates in the bulk and the surface of MgO |
Author: | Domínguez-Ariza, David Sousa Romero, Carmen Illas i Riera, Francesc Ricci, Davide Pacchioni, Gianfranco |
Keywords: | Defectes cristal·lins Química de superfícies Química computacional Teoria del funcional de densitat Crystals defects Surface chemistry Computational chemistry Density functional theory |
Issue Date: | 2003 |
Publisher: | The American Physical Society |
Abstract: | Aggregates of oxygen vacancies (F centers) represent a particular form of point defects in ionic crystals. In this study we have considered the combination of two oxygen vacancies, the M center, in the bulk and on the surface of MgO by means of cluster model calculations. Both neutral and charged forms of the defect M and M+ have been taken into account. The ground state of the M center is characterized by the presence of two doubly occupied impurity levels in the gap of the material; in M+ centers the highest level is singly occupied. For the ground-state properties we used a gradient corrected density functional theory approach. The dipole-allowed singlet-to-singlet and doublet-to-doublet electronic transitions have been determined by means of explicitly correlated multireference second-order perturbation theory calculations. These have been compared with optical transitions determined with the time-dependent density functional theory formalism. The results show that bulk M and M+ centers give rise to intense absorptions at about 4.4 and 4.0 eV, respectively. Another less intense transition at 1.3 eV has also been found for the M+ center. On the surface the transitions occur at 1.6 eV (M+) and 2 eV (M). The results are compared with recently reported electron energy loss spectroscopy spectra on MgO thin films. |
Note: | Reproducció digital del document publicat en format paper, proporcionada per PROLA i http://dx.doi.org/10.1103/PhysRevB.68.054101 |
It is part of: | Physical Review B, 2003, vol. 68, núm. 5, p. 054101-1-054101-9 |
URI: | http://hdl.handle.net/2445/10809 |
Related resource: | http://dx.doi.org/10.1103/PhysRevB.68.054101 |
ISSN: | 0163-1829 |
Appears in Collections: | Articles publicats en revistes (Ciència dels Materials i Química Física) |
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