Three-band Anderson-Mott-Hubbard model for the metal-insulator transition in cubic disordered tungsten bronzesNaxWO3and

H. Dücker¹,

W. von Niessen²,

Thorsten Koslowski

³

et al.

Variational Approach to the Energetics of Small Polaron Formation and Hopping in Tungsten Oxides

“…As discussed in Ref. [8], in the presence of only a single conduction band electron, the results are not sensitive to spin polarization, whereas we believe the conductivity and the formation of magnetic moments in the regime of all but the smallest degrees of doping being determined by the on-site repulsion between electrons populating transition metal d orbitals, as put forward by Dücker et al [10].…”

“…Following Dücker et al in their study of a repulsive Anderson-Mott-Hubbard model of the tungsten bronzes, we restrict the computation of the charges relevant to the electron-electron interactions to conduction band eigenstates and thus interprete the tungsten site energies as effective ones, incorporating a constant contribution from interactions between charges accumulated in the valence band [10]. We use W − O = 3.17 eV and |V pdπ | = 1.6 eV [10].…”

“…To describe the geometry, we use the cubic ReO 3 structure. In the small x regime, oxygen defects or potassium doping are solely interpreted as inducing electron donation, we ignore the possibility of interactions between structural defects and electrons [10] and the formation of line defects [11]. The electronic structure is described by a nearest-neighbour tightbinding Hamiltonian.…”

Synthesis and electrical properties of cubic NaxWO3 thin films across the metal–insulator transition

“…Investigation of MIT on tantalum substituted Na x WO 3 assumed significance mainly due to the absence of structural changes in the system on varying the sodium content. Various models including those of Anderson-Mott-Hubbard [20,21] and the percolation approach [3,4] have predicted semiconducting behaviour for Na x WO 3 below a certain critical sodium concentration. The transition point was predicted to be x c = 0.18 and 0.16, respectively, by Anderson-Mott-Hubbard and the percolation models.…”

Refractory metals in molten salts: Theory and simulation of geometry, electronic structure, and electron transport

“…Following recent numerical work on doped and disordered sodium tungsten bronzes, 29 we restrict the computation of expectation values of the number operator to conduction band eigenstates, with the advantage that all one-electron tight-binding parameters entering the Hamiltonian ͑2.3.1͒ are unaltered for a system with an empty conduction band, as compared to the tight-binding model Eq. ͑2.2.1͒.…”