Structural phase transition, elastic and electronic properties of TmSb and YbSb: A LSDA + U study under pressure

Abstract

The full-potential linear augmented plane wave plus local orbital method employing the local spin-density approximation (LSDA) along with Hubbard-U corrections and spin–orbit coupling has been used to study the electronic, structural, phase transition and elastic properties of TmSb and YbSb. Under compression they undergo first-order structural transition from B1 → B2 phase. The computed phase transition pressures are 21.74 and 13.57 GPa which agrees well with their measured values ∼22.0 and 13 GPa. The structural properties viz., equilibrium lattice constants, bulk modulus and its pressure derivative and volume collapse are also in closer agreement with their experimental data. The elastic constants and their combinations: Young's and Shear moduli, Poisson's ratio, Zener anisotropy factor, Lame's coefficients, Kleinman parameter and Debye temperature of these compounds have been computed at normal pressure. These values are in good agreement with experimental data. The LSDA + U strategy shows significant impact on the energy levels of the occupied and unoccupied 4f states in the electronic structure of both the compounds. The LSDA + U method provides better description of crystal properties of present system.