High-pressure structural phase transition and electronic properties of the alkali hydrides compounds XH (X = Li, Na)

Abstract

ABSTRACTFirst principle calculations based on the density functional theory using the full-potential linearized augmented plane wave method have been carried out to determine the structural stability of different crystallographic phases, the pressure-induced phase transition and the electronic properties of LiH and NaH compounds. The rocksalt, zincblende, cesium chloride (CsCl) and wurtzite structures are considered. The exchange and correlation potential is treated by using the improved generalized-gradient approximation Moreover, the modified Becke–Johnson (mBJ) scheme is also applied to optimize the corresponding potential for the band structure calculations. The calculated ground state parameters for these compounds in each structure are well compared with the available theoretical and experimental results. The calculated band structures using the mBJ-GGA approach have an insulating nature for both compounds in all the considered structures, except the LiH for CsCl structure which shows a semi-conducting behavior. The results are in good agreement with other calculations and experimental measurements.