Electronic structure and properties of superconducting LiTi2O4

We present results of precise local-density calculations of the electronic structure for the superconducting spinel oxide LiTi2O4 as obtained with the full-potential linearized augmented-plane-wave method. Self-consistent calculations are performed for both the observed (distorted) and ideal (undistorted) spinel structures. The results show important changes in the electronic states near EF between the two structures. Unlike the case of Cu d states in the high-Tc Cu-O superconductors, the Ti d bands are separated by an 2.6-eV energy gap from the O p bands, and are further split into t2g and eg bands. The states around EF have predominant Ti d character, with a substantial hybridization with O p states. Crude rigid-ion calculations indicate that, unlike the case of the Cu-O materials, superconductivity of LiTi2O4 can be due to an electron-phonon mechanism.