LAUSR

Abstract The structural, mechanical, lattice dynamics and thermophysical characteristics of XC2 (X = La, Ce, Tb, Ho) have been theoretically investigate by means of density functional theory (DFT). The optimized lattice constants and elastic constants of XC2 (X = La, Ce, Tb, Ho) are in an excellent agreement with the available experimental data. The elastic moduli including elastic constants Cij, bulk modulus B, shear modulus G, Young's modulus E, Debye temperature θ, wave velocities and anisotropy indexes have been predicted successfully. The brittle/ductile properties of four compounds are determined by the ratio of B/G. According to the values of anisotropic indexes, three dimensional (3D) surface constructions indicate that XC2 shows mechanical anisotropy. Results indicate that four compounds can be stabilized mechanically and dynamically in the ground state phase of the tetragonal structure. The thermophysical characteristics such as internal energy, Helmholtz free energy, entropy and the constant volume specific heat under high temperatures are also predicted and analyzed comprehensively based on phonon density of states.