The positions of the interstitial fluoride atoms in LiBaF3 crystal were simulated. It was found that the formation energy was low when interstitial fluoride atoms at the center of the edge of the cube formed by Ba ions. The electronic structures and absorption bands for the perfect LiBaF3 crystal and the LiBaF3 crystal containing interstitial fluoride were calculated using a density functional theory code. It was predicted that the interstitial fluoride atom combine with a formal lattice fluoride ion forming H center caused the 320nm absorption band.

First-Principles Study of LiBaF3 Crystals Containing Interstitial Fluoride. H.Qiao, T.Liu, Q.Zhang, F.Cheng, X.Zhou: Current Applied Physics, 2010, 10[5], 1286-9