Symmetry considerations on band filling and first optical transition in NiO John E. Petersen, Luisa M. Scolfaro, Pablo D. Borges and Wilhelmus J. Geerts Eur. Phys. J. B, 92 10 (2019) 232 Published online: 10 October 2019 DOI: 10.1140/epjb/e2019-100363-5