Near degeneracy and pseudo Jahn-Teller effects in mixed-valence ladders: the phase transition in NaV$_2$O$_5$
arXiv:cond-mat/0501757 · doi:10.1103/PhysRevB.72.195117
Abstract
We analyze the electronic structure of a mixed-valence ladder system. We find that structural anisotropy and complex electron correlations lead to on-rung charge localization and insulating character. Charge fluctuations within the rung of the ladder interact strongly to the lattice degrees of freedom, which gives rise to large pseudo Jahn--Teller effects. The phase transition in NaV$_2$O$_5$ should be driven by this kind of mechanism.
5 pages, 2 figures, 1 table, submitted to PRL