First-principles investigation of mechanical and thermodynamic properties of the rare earth intermetallic YbAl 3 under pressure

Abstract

First-principles calculations are used to study the elastic, electronic, vibrational and thermodynamic properties of the rare earth intermetallic YbAl 3 under pressure up to 41.9 GPa. Using the total energy calculations combined with the shear-strain method and phonon calculations, we found that YbAl 3 has good mechanical and dynamical stability at the pressure range in our study. The trends of elastic constants, bulk modulus and shear modulus varieties under pressure are predicted. Moreover, we have estimated the Debye temperatures of YbAl 3 under pressure from the average sound velocity. We have in addition analyzed the charge transfer, electronic structure, chemical bonding and lattice dynamic properties of YbAl 3 under pressure. We pointed out that the Al atoms play a more important role than Yb in the performance changes under pressure. Finally, predictions of the isochoric heat capacity C V , isobaric heat capacity C p and thermodynamic properties under various pressures for YbAl 3 are found to be comparable to the experimental results using the supercell phonon calculation and the quasi-harmonic approximation method.