The structural, mechanical, electronic, and optical properties of multiferroic LiCu2O2 under different pressures

Abstract

In this work, the structural, mechanical, and electronic properties of LiCu₂O₂ compound under different pressures were studied using the density functional theory. The spin-polarized generalized-gradient approximation has been used for modelling the exchange-correlation effects. In particular, the electronic structure under zero pressure was analysed using both conventional GGA-PBE and meta-GGA (mBJLDA) functional. The structural optimization was performed by using VASP-code, and the lattice parameters and magnetic moments were calculated. Bulk modulus, shear modulus, Young’s modulus, Poisson’s ratio, anisotropy factors, sound velocities, and Debye temperature were obtained from the calculated elastic constants for LiCu₂O₂ compound. While the electronic band structures obtained from both functionals for spin up under zero pressure are semiconductor in nature, the electronic band structures obtained from PBE and mBJLDA functionals for spin down are narrow semiconductor and semiconductor, respectively. For the spin-up state, the E_g value decreases linearly after 5 GPa, while the E_g value increases linearly for the spin-down state. The real and imaginary parts of the dielectric function along the x, y, and z axes and the optical constants, such as the energy loss function, refractive index, reflectivity coefficient, and extinction coefficient are also calculated and presented.