First Principles Investigations on Structural, Elastic, Electronic, and Optical Properties of Li2CdGeS4

First principles calculations have been carried out to investigate the crystal structure, elastic constants, chemical bonding, electronic and optical properties of Li2CdGeS4. The calculated equilibrium lattice constants, bulk modulus and its pressure derivative are in reasonable agreement with the available experimental results. We have predicted the elastic constants as well as bulk and shear moduli. By the elastic stability criteria, it is found that Li2CdGeS4 is mechanically stable and is a ductile system. Electronic and chemical bonding properties have been studied through the calculation of band structure, density of states and Mulliken population. We found that the energy band gap is 2.817 eV in LDA (2.421 eV in GGA) for Li2CdGeS4. Moreover the complex dielectric function, refractive index, extinction coefficient, absorption coefficient, reflectivity and loss function are also calculated, which show significant optical anisotropies in the components of polarization directions (1 0 0), (0 1 0) and (0 0 1).