The comparative study of structural, optoelectronic and thermoelectric properties of Li-based half-Heusler alloys via GGA and meta-GGA functionals

The present work aims to investigate the effects of meta-GGA functionals on the structural, optoelectronic and thermoelectric properties of LiXY(X=Be, Mg, Zn, Cd and Y=N, P, As, Sb, Bi) half-Heusler alloys using density functional theory (DFT) and classical Boltzmann transport theory. The obtained lattice constants of these alloys are in good agreement with the experimental values, exhibiting a slight decrease slightly with metaGGA functionals compared with GGA-PBE. Band structure calculations demonstrate that the materials exhibit semiconductor character and provide validation for the use of meta-GGA functionals, particularly the r2SCAN 2 SCAN and rSCAN, to predict the band gap values of LiXY more accurately. Optical and thermoelectric properties are calculated and discussed in detail. The results reveal that the meta-GGA functionals predict a significant change compared with GGA-PBE in the low energy and temperature region, while in the high energy and temperature regions, all four functionals present almost the same change trends.