Regular Article

Symmetry considerations on band filling and first optical transition in NiO

¹ Department of Physics, Texas State University, 78666 San Marcos, TX, USA
² Instituto de Ciencias Exatas e Tecnologia, Universidade Federal de Vicosa, Campus de Rio Paranaíba, Rio Paranaíba, 38810-000 MG, Brazil

^a e-mail: jepetersen@utexas.edu

Received: 19 July 2019
Published online: 10 October 2019

Abstract

Recent theoretical works on NiO have not agreed upon the nature of the first optical transition. By altering band filling – with highly concentrated O vacancies and Fe impurities – here, the orbital density of states is changed near the Fermi energy. The variation in optical properties, relative to the changes in orbital character, along with group theory analysis of hybridized orbitals, provides new insight when evaluating the first optical transition of NiO. Here, based on density functional theory, the first optical transition is found to have two possibilities – either superexchange site-hopping or a transition from the hybridized e_g state to the hybridized a_1u state, rather than the intra-atomic transitions which are causing disagreement in the recent literature.