An ab initio study of electronic structure and optical properties of multiferroic perovskites PbVO3 and BiCoO3

Within density functional theory (DFT) with the generalized gradient approximation (GGA), GGA plus on-site Coulomb repulsion method, and improved version of the modified Becke-Johnson exchange potential suggested recently by Tran and Blaha [F. Tran, P. Blaha, Phys. Rev. Lett. 102 (2009) 2264011 (TB-mBJ), we investigate the electronic structure and optical properties of noncentrosymmetric multiferroic perovskites PbVO3 and BiCoO3. These two compounds, although similar in lattice distortions and population of crystal-field levels, behave quite differently because of the different interplay between the fundamental Kramers degeneracy and the single-ion anisotropy in them. The main characteristic of the calculated TB-mBJ electronic structures is significant rearrangement of the V and Co 3d states near their valence bands tops when compared to the present and earlier GGA and GGA + U calculations of these compounds. This fact causes the different optical responses of the title compounds as well, which are analyzed and interpreted in terms of the calculated electronic structures. A comparison of the calculated properties with available experimental data indicates that the TB-mBJ approach provides a better description of the electronic and optical properties of PbVO3 and BiCoO3 than the standard GGA and GGA + U approaches. (c) 2013 Elsevier B.V. All rights reserved.