Comparative first-principles study of a prototypical Dirac semimetal by GGA and SCAN meta-GGA energy functionals

Density functional theory is widely used to study topological properties of materials, limitations of the underlying exchange-correlation functionals notwithstanding. In this connection, the recently constructed strongly-constrained-and-appropriately-normed (SCAN) meta-GGA exchange-correlation functional has shown significant improvements in many classes of materials. Here we discuss SCAN-based electronic properties of the prototypical Dirac semimetal Na₃Bi and compare our results with those based on the commonly used generalized gradient approximation (GGA). In particular, SCAN yields a spin-orbit coupling driven topological phase transition from the normal insulator to Dirac semimetal state in contrast with the GGA results. SCAN produces Dirac-node locations, Fermi velocities and s-band shift around the Γ point that are in better accord than the GGA predictions with the corresponding experimental results.