Ab initio investigation of the crystal and electronic structures of the nitride fluoride ThNF

A revisit of the early crystal structure determination of rhombohedral ThNF is done using DFT based methods. From full geometry optimizations and energies, an insulating ground state with updated atomic coordinates is identified in better agreement with an iono-covalent chemical picture showing stronger Th–N bonding versus Th–F and d(Th–N) < d(Th–F). A comparison with tetragonal ThNCl homolog is presented.

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► ThNF crystal structure is revisited with DFT based calculations.
► Optimized atomic positions lead to larger d(Th–F) than d(Th–N).
► The nitride–fluoride is insulating with stronger Th–N bonds versus Th–F.
► Charges in ThNF/ThNCl provide assessment of ground state structures.