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 (I4(1)/amd No. 141). The new structural setups are identified with space groups I-4m2 No. 119 and Imm2 No. 94 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. (C) 2011 Elsevier Inc. All rights reserved.