Pressure induced phase transition, electronic and optical properties of LiBeX (XAs, Sb and Bi).

In this contribution, we report the results of theoretical calculation on the pressure induced phase transitions, structural, electronic and optical properties of the lithium based ternary LiBeX (X = As, Sb, Bi) compounds. These calculations are carried out using the full potential linearized augmented plane wave method. Our results show that these compounds undergo first order phase transitions.

Phase transitions and lattice dynamics in perovskite-type hydride [Formula: see text].

First principles calculations have been used to investigate the structural phase transitions and lattice dynamics in the alloy [Formula: see text]. The density functional perturbation theory and the virtual crystal approximation are employed, within the generalized gradient approximation. Our total energy and formation enthalpy results show that [Formula: see text] undergoes a phase transition from the orthorhombic Pnma phase to the polar R3c one at a lithium concentration of x  =  0.

Calculation of the vibrational properties of LiMgAs.

We have studied the vibrational properties of the filled tetrahedral semiconductor LiMgAs and its binary analog AlAs by using the plane-wave pseudopotential method within density functional theory. The calculated lattice constants for the studied compounds are in good agreement with previous theoretical and experimental results. The phonon dispersion curves and phonon density of states are calculated by using density functional perturbation theory.