Ab initio calculations of the elastic, vibrational, electronic properties, and electron-phonon constant of superconducting YB6 compound under low pressure

Abstract

The crystal structure, mechanical, electronic properties, as well as the electron-phonon constant of YB6 under low pressure (<1.0 GPa) were investigated by first-principles density functional theory (DFT) within the bounds of the generalized gradient approximation (GGA). The calculated cell parameter a at zero pressure is in good agreement with the reported experimental and theoretically data and decreases as pressure increases. Under pressure, the elastic constants and mechanical moduli increase while the hardness decreases. The calculated elastic constants reveals mechanical stability up to 1 GPa. Pugh's criterion and Poisson's ratio suggest that the compound has ductile behavior. The electronic density of states (DOS) under pressure shows a slight decrease due to reducing the B 2p states. Finally, the electron-phonon coupling constant (λ e−f ) was determined using the Debye temperature and the McMillan equation, the value found was λ e−f = 0.53 as a function of pressure; therefore, our results suggest that the YB6 is an intermediate coupling superconductor.