Partially Oxidized Transition-Metal Polymers; Stabilization of Mixed Valence States
The theoretical description of spatial hole-state properties in low-dimensional materials is a central problem in electronic structure theories of the solid state [IV.42–IV.45]. Two extreme solutions are in principle accesible in numerical methods that are formulated in any one-determinantal approximation. The removal of an electron can be described in terms of “spatially uncorrelated” Bloch orbitals under the assumption of the validity of Koopman’s theorem [IV.46]. Some time ago it had been suggested by Seitz that the description of hole-states in terms of delocalized Bloch orbitals is a physically reliable approximation in crystalline solids [IV.47]. In the past years the spatial localization properties of holes have been reinvestigated by Kunz and coworkers in simple narrow-band insulators of the Mott-Hubbard type. Energetic consequences of electron removal from localized orbitals of the Heitler-London type have been studied by elaborate computational methods [IV.42,IV.43,IV.48].
KeywordsCharge Density Wave Symmetry Reduction Coherent Potential Approximation Mixed Valence State Electron Removal
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