Electronic structure and anisotropic chemical bonding in TiNF from ab initio study

Accounting for disorder in anatase titanium nitride fluoride TiNF is done through atoms re-distributions based on geometry optimizations using ultra soft pseudo potentials within density functional theory DFT. The fully geometry relaxed structures are found to keep the body centering of anatase (I41/amd No. 141). The new structural setups are identified with space groups I-4m2 No. 119 and Imm2 No. 44 which obey the "group to subgroup" relationships with respect to anatase. In the ground state Imm2 structure identified from energy differences, TiNF is found semi-conducting with similar density of states features to anatase TiO2 and a chemical bonding differentiated between covalent like Ti-N versus ionic like Ti-F. Inter-anion N-F bonding is also identified. - Graphical Abstract: The geometry optimized ground state anatase derived TiNF structure with arrangement of open faceted TiN3F3 distorted octahedra. The insert shows the arrangement of octahedra in anatase TiO2. Highlights: ► Original approach of TiNF structure for addressing the electronic band structure. ► Based on anatase, two different ordering scheme models with geometry optimization. ► New structures obeying the group→subgroup relationships with Imm2 ground state from energy. ► In the ground state TiNF is found semi-conducting with similar density of states to anatase TiO2. ► Chemical bonding differentiated between covalent like Ti-N and ionic Ti-F.