The AV_nO_{2n+1} mixed valence compounds (n=1, A=Na) are classified as dimerized layered system with strongly interacting d-electrons of vanadium ions. The derived band gaps, energy dispersion relations and density of electronic states are in a good agreement with available experimental and theoretical data. The correlated band gap provides the insulating state of the high-temperature alpha-NaV_2O_5 phase whereas the state, earlier misrepresented as the spin-Peierls state, is governed, in fact, by opening of the Coulomb gap.
@article{arxiv.cond-mat/9909046,
title = {Effective Dimensionality and Band Structure of alpha-Nav_2o_5 Compound: 1D or 2D?},
author = {V. A. Ivanov and Z. V. Popovic and P. Khuong and V. V. Moshchalkov},
journal= {arXiv preprint arXiv:cond-mat/9909046},
year = {2019}
}