The SCAN Meta-GGA : An Efficient Universal Non-Empirical Semi-local Density Functional

The accuracy of the Kohn-Sham density functional theory is limited by the approximation to its exchange-correlation energy E_xc. Due to the computational efficiency of semi-local approximations that use as inputs only the electron density, its gradient, and the kinetic energy density, efforts are still made to improve the PBE GGA, the standard non-empirical semi-local density functional that is robust and universally applicable to different systems. Semi-local approximations are also bases for developing non-local density functionals that are needed for treating long-range effects (e.g., the van der Waals interaction and charge transfer), which further motivates such efforts. The SCAN semi-local density functional, the most sophisticated one so far [1] with systematic improvement over PBE with a comparable computational efficiency[2], represents a successful example of these efforts. Here, SCAN is further tested and gives promising performance on two difficult properties: the ground structure selections of about 300 binary solids and the metal-insulator-transition of a cuprate under doping.

[1] J. Sun, et al, Phys. Rev. Lett. 115, 036402 (2015). [2] J. Sun, et al, Nat. Chem. 8, 831 (2016).