Lithium intercalation into TiO${}_{2}$(B): A comparison of LDA, GGA, and GGA+$U$ density functional calculations

Lithium intercalation into TiO $_{2}$ (B): A comparison of LDA, GGA, and GGA+ $U$ density functional calculations

Benjamin J. Morgan and Paul A. Madden

Phys. Rev. B 86, 035147 – Published 27 July 2012

Abstract

Density functional theory has been used to study lithium intercalation into TiO $_{2}$ (B) at low to moderate concentrations [ $0 < x (Li) \leq 0.25$ ] with a range of density functionals: LDA, GGA (PW91, PBE, PBEsol), and GGA+ $U$ (PBE+ $U$ , PBEsol+ $U$ ), with the GGA+ $U$ calculations employing a Hubbard+ $U$ correction to the Ti $d$ states. LDA and GGA functionals give the same general behavior, whereas qualitatively different behavior is predicted by GGA+ $U$ for electronic structure and the order of stability of occupied intercalation sites. LDA/GGA functionals predict Li $_{x}$ TiO $_{2}$ (B) to be metallic, with the excess charge distributed over all the Ti sites. In contrast, GGA+ $U$ predicts defect states in the band gap corresponding to charge strongly localized at specific Ti sites. All the considered functionals predict A1 and/or A2 site occupation at $x (Li) = 0.25$ , which challenges the interpretation of previous neutron data that, at this composition, the C site is preferentially occupied.