Semiempirical calculations on WO ₃ and M _X WO ₃ crystals (M = H, Li, Na)

Abstract

ABSTRACT:The monoclinic structure of tungsten trioxide WO has been studied by 3 Ž . combining a modified intermediate neglect of differential overlap INDO method and the supercell model. The fitted semiempirical parameters describe very well the features of the band structure and crystal structure. Calculations of H, Li, and Na impurities in a WO crystal have been performed to study the absorption spectra and the equilibrium 3 geometries of intercalated impurities.

Polaron absorption in amorphous tungsten oxide films

“…Most band structure calculations have considered crystalline WO 3 . [21][22][23][24] Recently, a calculation for amorphous WO 3 has also appeared. 25 This indicates that the amorphous structure leads to localizations of the lower part of the conduction band.…”

Oxygen vacancy in cubic WO3 studied by first-principles pseudopotential calculation

“…Deb's vacancy model [1] suggests that the oxygen vacancy (V O ) is involved in the optical transition; while all the other models suggest that the optical transition occurs via the charge transfer between non-equivalent W sites in one way or the other [4 -6]. It is found in Ref.[7] that the electrochromic colouration efficiency and conductivity is enhanced, and the peak energy of the mid-gap absorption shifts to the higher energy, with increasing oxygen deficiency.There have been numerous theoretical studies on the electronic structure of WO 3 with and without ion intercalation: non-self-consistent and/or semi-empirical calculations [8][9][10][11], and self-consistent first-principles calculations [12 -16]. However, no publications on the theoretical study of V O in WO 3 system either with or without the intercalation have been found except for one for amorphous WO 3 [17].…”

“…There have been numerous theoretical studies on the electronic structure of WO 3 with and without ion intercalation: non-self-consistent and/or semi-empirical calculations [8][9][10][11], and self-consistent first-principles calculations [12 -16]. However, no publications on the theoretical study of V O in WO 3 system either with or without the intercalation have been found except for one for amorphous WO 3 [17].…”

Structural and electronic effects of an Nb impurity in PZT crystals

“…It is important to note that the relativistic effects for the Pb atom were indirectly taken into account by reproducing the PbTiO 3 crystal band structure properties [26]. This was accomplished, as previously published for the W atom [31], by manipulating the atomic parameters and incorporating special pseudopotentials into our computer code [32]. An important feature of these pseudopotentials is that relativistic effects are included that also enable them to be used in nonrelativistic formulations.…”