First-principles calculations of the mechanic and vibration properties of AgRE (RE = Ho, Er, Tm) intermetallic compounds under pressure

Abstract

First-principles calculations are used to investigate the structural, elastic and vibration properties of the binary intermetallic compounds AgRE (RE = Ho, Er, Tm) with a B2 (CsCl) structure using density functional theory. The calculated structural parameters, the bulk modulus and its derivative with respect to pressure are in good agreement with experimental and numerical data. Additionally, the negative energy of formation of AgRE (RE = Ho, Er, Tm) with a B2 structure is examined. The independent second order elastic constants and their related properties, which are essential for mechanical stability, are investigated under pressure (0-60 GPa). The phonon spectra and phonon density of states are also discussed. All calculated phonon modes for AgRE (RE = Ho, Er) are positive in the phonon dispersion diagrams.