The origin of the gap in NiS2 as well as the pressure- and doping-induced metal-insulator transition in the NiS2-xSex solid solutions are investigated both theoretically using the first-principles band structures combined with the dynamical mean-field approximation for the electronic correlations and experimentally by means of infrared and x-ray absorption spectroscopies. The bonding-antibonding splitting in the S-S (Se-Se) dimer is identified as the main parameter controlling the size of the charge gap. The implications for the metal-insulator transition driven by pressure and Se doping are discussed.
@article{arxiv.0907.1745,
title = {Metal-insulator transition in NiS$_{2-x}$Se$_x$},
author = {J. Kunes and L. Baldassarre and B. Schachner and K. Rabia and C. A. Kuntscher and Dm. M. Korotin and V. I. Anisimov and J. A. McLeod and E. Z. Kurmaev and A. Moewes},
journal= {arXiv preprint arXiv:0907.1745},
year = {2010}
}