First-principles study on the electronic, optical and thermodynamic properties of ABO3 (A = La,Sr, B = Fe,Co) perovskites

The electronic, optical and thermodynamic properties of ABO(3) (A - La, Sr, B - Fe, Co) perovskites are investigated using first-principles calculations. The obtained results indicate that SrCoO3 and SrFeO3 are metals, while LaCoO3 and LaFeO3 are insulators and all of them exhibit strong hybridization of the Fe/Co-3d and O-2p orbitals. By correlating the energy band structures with the peaks of the imaginary part of the dielectric function, we obtained the origin of each electron excitation to provide information about the active bands for the corresponding optical transitions observed in the experiment. Moreover, the Debye temperatures theta(D) obtained from the phonon frequencies are comparable to the available data. Finally, the thermodynamic properties of the Helmholtz free energy F, entropy S, and constant-volume heat capacity C-v are investigated based on the phonon spectra.