The investigation of the structural, electronic, mechanic, and vibrational properties of GeI2, Re2C, La-Bi, AND Ln2O3 (Ln=Sc, Y, La-Lu) compounds with Ab initio method

In this study, the structural, electronic, elastic, and vibrational properties of GeI2, Re2C, La-Bi (La2Bi, LaBi2, La4Bi3, La5Bi3), and Ln2O3 (Ln=Sc, Y, La-Lu) compounds were calculated using one of the LDA and/or GGA approximation with ab-initio methods based on density functional theory (DFT). GeI2 compound in the C6, C19, C35, C22, C23 and C1, Re2C compound in the ReB2, La-Bi compounds in the La2Sb, HfGa2, anti-Th3P4, and Mn5Si3, and the lanthanide sesquioxide in the A, B, C-type structures were analyzed. Specifically, some fundamental physical quantities such as lattice parameters, probable phase transition pressures, band structures, elastic constants, shear modulus, Youngs modulus, and Poisson?s ratio of the investigated compounds were computed. The phonon dispersion curves and the phonon density of states of some compounds were, also, calculated. The obtained results were compared with the existing experimental and other theoretical ones. Our overall results showed that the used methods have given the satisfactory description for the physical properties of the studied compounds.