A comparative study for structural and electronic properties of single-crystal ScN

A comparative study by FP-LAPW calculations based on DFT within LDA, PBE-GGA, EVex-PWco-GGA, and EVex-GGA-LDAco schemes is introduced for the structural and electronic properties of ScN in RS, ZB, WZ, and CsCl phases. According to all approximations used in this work, the RS phase is the stable ground state structure and makes a transition to CsCl phase at high transition pressure. While PBE-GGA and EVex-PWco-GGA's have provided better structural features such as equilibrium lattice constant and bulk modulus, only EVex-PWco-GGA and EVex-GGA-LDAco's have given the non zero, positive indirect energy gap for RS-ScN, comparable with the experimental ones. The indirect band gap of ScN in RS phase is enlarged to the corresponding measured value by EVex-PWco-GGA+USIC calculations in which the Coulomb self and exchange-correlation interactions of the localized d-orbitals of Sc have been corrected by the potential parameter of U. The EVex-PWco-GGA calculations have also provided good results for the structural and electronic features of ScN in ZB, WZ, and CsCl phases comparable with the theoretical data available in the literature. EVex-PWco-GGA and EVex-PWco-GGA+USIC schemes are considered to be the best ones among the others when the structural and electronic features of ScN are aimed to be calculated by the same exchange-correlation energy approximations.