Structural, elastic, and lattice dynamic stability of yttrium selenide (YSe) under pressure: A first principle study

Abstract

Ab initio calculations on structural, elastic and dynamic stability of CdO at high pressures J. Appl. Phys. 112, 093523 (2012); 10.1063/1.4764899First-principles investigations of elastic stability and electronic structure of cubic platinum carbide under pressure Structural, elastic, and lattice dynamical stability of YSe has been investigated as a function of pressure through first principles electronic band structure calculations. The comparison of enthalpies of rocksalt type (B1) and CsCl type cubic (B2) structures determined as a function of pressure suggests that the B1 phase will transform to B2 structure at $32 (30 GPa at 300 K obtained from comparison of Gibbs free energy at 300 K). The transition is identified to be of first order in nature with a volume discontinuity of $6.2% at the transition pressure. Furthermore, the theoretically determined equation of state has been utilized to derive various physical quantities, such as zero pressure equilibrium volume, bulk modulus, and pressure derivative of bulk modulus. The single crystal elastic constants have been predicted at various pressures for both the B1 and B2 structures using the energy strain method. The activation barrier between B1 and B2 phases calculated at transition point is $19.7mRy/formula unit. Our lattice dynamic calculations show that both the B1 as well as B2 structures are lattice dynamically stable not only at ambient pressure but also at transition pressure. The B1 phase becomes lattice dynamically unstable at $112 GPa, i.e., much beyond the transition pressure. The effect of temperature on volume and bulk modulus of the YSe in B1 phase has also been examined. V C 2014 AIP Publishing LLC.

Prediction of new high pressure structural sequence in thorium carbide: A first principles study

“…Further, these elastic constants have been utilized to determine the zero pressure Debye temperature (h D ) following the procedure described in the Ref. 37 elastic constants are further extended to high pressures. Fig.…”

Lattice thermal conductivity of LaSe

“…However, since the mass of La atom is much larger than the mass of Se (mass ratio 1.76), there is a gap between longitudinal acoustic (LA) and TO in phonon dispersion curves of LaSe, which suggests weak interaction between the optical modes and acoustic modes. Recently, Sahoo et al performed similar phonon properties calculations on YSe [23]. As shown in Fig.…”