Density functional theory calculations of the bandstructure of cubic boron arsenide

A bandgap of cubic boron arsenide (cBAs) is systematically calculated using various approaches in density functional theory (DFT). We explore how basis set, atomic potential, exchange–correlation functional, and spin–orbit coupling influence the bandgap calculations when using Synopsis QuantumATK (QATK), Quantum ESPRESSO, and VASP codes. Our measurements of indirect and direct bandgaps serve as reference values. We found that using a linear combination of atomic orbitals (LCAO) with an ultra basis set, Pseudo-Dojo norm-conserving pseudopotentials, the HSE06 hybrid exchange–correlation functional, and non-collinear spin–orbit coupling (NSOC) in QATK DFT calculations yields indirect and direct bandgaps of 2 . 03 eV and 3 . 99 eV , which are very close to our measurements of 2 . 01 eV and 4 . 24 eV , and recent experimental results of 2 . 02 eV and 4.12 eV, respectively. NSOC is critical for accurate bandstructure calculations in relatively wide bandgap materials, and the HSE06 functional and optimised PseudoDojo pseudopotentials play a similar role. Using the more common generalised gradient approximation (GGA) exchange–correlation functional PBE underestimates the indirect and direct bandgaps, with values ranging from 1 . 13 eV to 1 . 36 eV and from 3 . 04 eV to 3 . 37 eV , respectively, depending on the type of basis set, potential, and spin–orbit coupling used. • Identified optimal exchange-correlation, matched bandgaps via infrared spectroscopy. • Calculated the bandstructure of cubic boron arsenide, a promising semiconductor. • Revealed impact of spin-orbital coupling on bandstructure in cubic boron arsenide. • Explored methods in DFT to reproduce experimental bandgap in cubic boron arsenide.