  The octahedral tilting and ferroelectric-like structural transition of LiOsO3
metallic perovskite [Nature Materials 12, 1024 (2013)] was examined using
first-principles density-functional theory. In LiOsO3, a-a-a- octahedral
titling mode is responsible for the cubic to rhombohedral structural
transition, which is stable phase at room temperature. At low temperatures, a
non-centrosymmetric transition to a rhombohedra phase was realized due to zone
center phonon softening. The phase transition behavior of LiOsO3 can be
explained fully by density functional calculations and phonon calculations. The
electronic structure and Fermi surface changes due to the electron lattice
coupling effect are also presented. The carrier density of state across the
phase transition is associated with the resistivity, heat capacity, and
susceptibility.
