The structural, elastic, electronic, and optical properties of the rhombohedral La₂NiMnO₆ double perovskite compound at different temperatures

Abstract

This study investigates the structural, mechanical, electronic, and optical properties of the rhombohedral $La_2NiMnO_6$ (LNMO) perovskite compound at different temperatures using density functional theory. The calculation employed the spin-polarized generalized gradient approximation (GGA). The calculated lattice parameter values agree (less than 1.2 % difference) with experimental values. We determined the mechanical properties using elastic constants calculated from the stress-strain relationship. The elastic constants obtained satisfy the Born stability criteria for the rhombohedral structure. Electronic band structure calculations revealed that LNMO exhibits the suitable narrow band gap semiconductor character in the spin-polarized state. Finally, the real and imaginary parts of the dielectric function and other optical functions along the x and z directions are calculated and interpreted.