Title: First principles investigations of electronic, magnetic and bonding peculiarities of uranium nitride-fluoride UNF,
Abstract: Based on geometry optimization and magnetic structure investigations within
density functional theory, unique uranium nitride fluoride UNF, isoelectronic
with UO2, is shown to present peculiar differentiated physical properties. Such
specificities versus the oxide are related with the mixed anionic sublattices
and the layered-like tetragonal structure characterized by covalent like
[U2N2]2+motifs interlayered by ionic like [F2]2- ones and illustrated herein
with electron localization function graphs. Particularly the ionocovalent
chemical picture shows, based on overlap population analyses, stronger U-N
bonding versus N-F and d(U-N) < d(U-F) distances. Based on LDA+U calculations
the ground state magnetic structure is insulating antiferromagnet with 2 Bohr
Magnetons magnetization per magnetic subcell and ~2 eV band gap.