Etude ab initio des propriétés structurales, électroniques et dynamiques du composé LiBeAs.

Abstract

In this work, we studied the structural, electronic, and vibrational properties of the LiBeAs compound in its tetragonal (Cu2Sb-type) and hexagonal (LiGaGe-type) phases, using ab initio calculations based on density functional theory (DFT). The calculations were performed using the pseudopotential and plane-wave method. The exchange-correlation potential was treated within the generalized gradient approximation (GGA). We determined the structural parameters as well as the bulk moduli. A first-order phase transition between the two structures was predicted under the effect of pressure. From an electronic standpoint, the compound exhibits an indirect band gap in both phases. The phonon spectra, obtained using the DFPT method, show that all frequencies are positive, confirming the dynamical stability of both structures. The electronic density of states was also computed. Finally, the dielectric constants and Born effective charges were evaluated, completing the characterization of the material. The results were compared with theoretical and experimental data available in the literature.