First-principle investigation of Jahn–Teller distortion and topological analysis of chemical bonds in LiNiO2

First-principle GGA+U calculations were performed on the undistorted rhombohedral R3̄m model, the collinear Jahn–Teller distorted monoclinic C2/m model, and six non-collinear Jahn–Teller distortion ordering models of LiNiO2. The zigzag and C2/m models are found to be the most stable and the next most stable structural models, respectively. An energy gap appears for the C2/m and zigzag structures, whereas no energy gap appears for the R3̄m structure. Topological analyses were performed on the R3̄m, C2/m and zigzag models using the atoms-in-molecules theory and the electron localization function. The results show that the Ni–O interaction is the transit closed-shell interaction, in which the net electron transfer occurs from the Ni ion to the ligand O ions. The Ni–O bond possesses the σ dative bond character and is polarized toward the O ions. In the distorted structures, the bonding electrons around the oxygen atom are strongly polarized toward the long Ni–O bond.

Isosurfaces of the difference charge density and the electron localization function for the zigzag structure of LiNiO2.Figure optionsDownload as PowerPoint slideHighlights
► Using ELF and AIM, topological analyses were carried out on different structures.
► The zigzag Jahn–Teller distortion ordering is the most stable structure.
► Semiconductor gap emerges in the C2/m and zigzag structures.
► The Ni–O bonds are dative bonds.
► In the distorted structures, bond electrons accumulate in the long Ni–O bond basins.