Ab-initio study on the electronic, optical and ferroelectric properties of LiOsO3

A comprehensive investigation has been made on the ground state, magnetic, ferroelectric and optical properties of the recently synthesized ferroelectric-like LiOsO3 by first-principle calculations. It is found that the ground state of perfect LiOsO3 is G type antiferromagnetic (G-AFM) order by both LSDA + U with U-eff > 0 eV and HSE. For the G-AFM order, when U-eff > 1.75 eV the charge gap opens for LiOsO3 while the gap is about 0.60 eV by HSE. So the perfect LiOsO3 should be a G-AFM semiconductor. As for the Li-defected Li0.94OsO3, the Fermi level shifts to the valence bands. On the other hand the translational periodicity is destroyed by various defects, leading to the disappearance of magnetic order which is responsible for the ferroelectric metal state observed in experiment. This is proved by the decrease of the Os average magnetic moments of Li-defected LiOsO3. The calculated spontaneous polarization of perfect LiOsO3 is about 22.23 mu C/cm(2) and the largest component of second order nonlinear optical coefficient is 80.795 pm/V, which indicate that it should be a potential ferroelectric and nonlinear optical material. (C) 2015 Elsevier B.V. All rights reserved.