Elastic and Thermal Properties of Terbium Dihydride: an Ab-initio Study

The elastic and thermal properties of TbH2 compound were studied using the density functional theory (DFT) for temperature ranges from 0 to 800 K within the local density approximation (LDA) pseudopotential. The elastic constants and mechanical properties such as bulk modulus B, Young's modulus E, shear modulus G(H), Poisson's ratio sigma, Debye temperature (circle minus(D)), and sound velocities (v(m)) of TbH2 compound were investigated. Moreover, the first principles density functional perturbation theory (DFPT) as implemented in the quasi-harmonic approximation (QHA) was used for the calculation of the thermal properties like vibrational energy Delta F, entropy S, internal energy Delta E and constant-volume specific heat C-V of the TbH2. The obtained B/G ratio is 2.51, which reveals the good ductility of the TbH2 compound.