Structural, elastic, vibrational, electronic and optical properties of SmFeO3 using density functional theory

We perform first principles simulations for the structural, elastic, vibrational, electronic and optical properties of orthorhombic samarium orthoferrite SmFeO3 within the framework of density functional theory. A number of different density functionals, such as local density approximation, generalized gradient approximation, Hubbard interaction modified functional, modified Becke-Johnson approximation and Heyd-Scuseria-Ernzerhof hybrid functional have been used to model the exact electron exchange-correlation. We estimate the energy of the ground state for different magnetic configurations of SmFeO3. Its crystal structure is characterized in terms of calculated lattice parameters, atomic positions, relevant ionic radii, bond lengths, bond angles and compared with experimental values. The stability of its orthorhombic structure is simulated in terms of elastic properties. The vibrational phonon modes are calculated using density functional perturbation theory and are shown to be consistent with recent experimental observations. In case of electronic properties, we provide estimates based on density functionals with varying degrees of computational complexities in the Jacob's ladder. We show Heyd-Scuseria-Ernzerhof density functional theory provides better modelling for localized d and f orbitals in SFO which is in line with theoretical work on other rare-earth materials. The linear optical properties in terms of complex dielectric function and other standard optical functions are derived for Hubbard corrected generalized gradient approximation in combination with Fermi's golden rule.These provide a good theoretical analysis of structural, elastic, vibrational, electronic and optical properties of SFO.