Electronic Correlations and “Relaxations” in One-Dimensional (Organometallic) Polymers

Abstract

The strength and influence of corrections beyond the mean-field description (quasi-particle (QP) picture; i.e. electronic correlations and “relaxations”) on the band structures of low-dimensional materials has been the subject of detailed theoretical investigations [III.72–III.86]. The SCF methods that are used as prerequisite for the determination of QP corrections span the range from traditional APW or OPW schemes to CO approaches on the basis of ab initio and semiempirical Hamiltonians. Remarkable shifts of ε(k) curves due to QP interactions and pronounced graduations of these corrections as a function of the localization properties of the one-electron (band) states have been observed in solids that contain transition-metal atoms [III.85, III.86]. Relations between band structure properties, electronic intracell (intrasite) repulsions and the strength of QP corrections have been discussed for simple transition-metal oxides (e.g., Mott insulators, MnO, FeO, CoO, NiO) [III.87–III.92] and transition-metal polymers with organic π ligands [III.85,III.86,III.93,III.94]. The degree of sophistication of any many-body approach is of course determined by the complexity of the studied low-dimensional material (i.e. structural boundaries).