Periodic models in quantum chemical simulations of F centers in crystalline metal oxides

Abstract

ABSTRACT:We present a survey of recent first principles simulations of the neutral oxygen vacancies (F centers) existing as native or radiation-induced point defects in various crystalline metal oxides in different forms (bulk, bare substrate surface, and on the interface with metal adsorbates). We mainly consider periodic models in calculations of point defects using the metal oxide supercell or cyclic clusters. We compare different formalisms of first principles calculations, mostly the Density Functional Theory (DFT) as implemented in the framework of either localized basis set of atomic orbitals or delocalized basis sets of plane waves. We analyze in detail the structural and electronic properties of F centers in binary oxides of light metals (MgO and Al 2 O 3 ), and ternary metal oxides (SrTiO 3 , BaTiO 3 , PbTiO 3 , KNbO 3 , and PbZrO 3 perovskites). When available, we compare results of ab initio periodic defect calculations with experimental data, results of the first principles cluster calculations (both embedded and molecular) as well as with semi-empirical calculations. © 2007 Wiley Periodicals, Inc. Int J Quantum Chem 107: 2956 -2985, 2007 Key words: ab initio periodic calculations; binary and ternary metal oxides; bulk; bare substrate surfaces; metal/oxide interfaces; neutral F centers (oxygen vacancies); point defect formation and migration; electronic properties of defective metal oxides

Scaling reducibility of metal oxides

“…Upon formation of the oxygen vacancy, the DOS exhibits a state in the gap as corresponds to an F-center, located above the valence band by 2.57 eV (PBE) , 3.06 eV (B3LYP). This is in good agreement with experimental and comparable theoretical results [88,89,87].…”

“…The Mg 2+ and O 2-ions are octahedral and the bonding is highly ionic. The measured band gap in magnesium oxide is 7.8 eV [87]. Our PBE value of 4.77 eV, although underestimates the experimental one as expected from DFT-GGA, clearly reproduces the energetic gap of an insulating system.…”

“…MgO, see for instance [86,87]. The Mg 2+ and O 2-ions are octahedral and the bonding is highly ionic.…”

Surface structure for Au on (001) SrTiO3

“…The structural and electronic properties of oxygen vacancy in both the bulk and on the surface of STO were illustrated detailedly in Ref. [45]. Meanwhile, the structure of Au 0 O is also energetically favorable, which may be attributed to the highest electron affinity of Au atoms and electron transfer from electron-rich oxygen vacancy sites into Au atoms [46].…”

Oxides of third period elements revisited: synthesis, structure and photoluminescence properties of silica, magnesia, and alumina

“…59), 60) In MgO crystals, it has been demonstrated that there exist two principal oxygen vacancies, namely, the F + (an oxygen vacancy occupied by one electron) and F (an oxygen vacancy occupied by two electrons) color centers, which are oxygen vacancies with one and two electrons, respectively. Both the F + and F color centers absorb essentially the same energy of ³5 eV (³250 nm) but show different photoluminescence (PL) bands peaked at ³400 and ³500 nm, respectively.…”