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2003

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Si us plau utilitzeu sempre aquest identificador per citar o enllaçar aquest document: https://hdl.handle.net/2445/10809

Ground- and excited-state properties of M-center oxygen vacancy aggregates in the bulk and the surface of MgO

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Recurs relacionat

http://dx.doi.org/10.1103/PhysRevB.68.054101

Resum

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.

Matèries

Defectes cristal·lins, Química de superfícies, Química computacional, Teoria del funcional de densitat

Matèries (anglès)

Crystals defects, Surface chemistry, Computational chemistry, Density functional theory

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Articles publicats en revistes (Ciència dels Materials i Química Física)

Citació

DOMÍNGUEZ-ARIZA, David, et al. Ground- and excited-state properties of M-center oxygen vacancy aggregates in the bulk and the surface of MgO. Physical Review B. 2003. Vol. 68, num. 5, pags. 054101-1-054101-9. ISSN 0163-1829. [consulted: 15 of August of 2026]. Available at: https://hdl.handle.net/2445/10809

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