Periodic DFT

All periodic calculation are performed in VASP-5.4.4. The Perdew, Burke, and Ernzerhof (PBE) exchange-correlation functional is implemented with electron-ion interactions that are described by the projector augmented-wave (PAW) method and full periodic boundary conditions. The kinetic energy cutoff for the plane-wave basis set is set to 600 eV, and a Gaussian smearing with a width of 50 meV was applied to the partial occupancies of Kohn-Sham orbitals. For unit cells, as implemented in the Materials Project, Monkhorst-Pack grids with 64 k-points per Å^-3 in the reciprocal space were applied to sample the first Brillouin zone, except for hexagonal cells where Gamma centered meshes with a similar k-point density is used. The convergence criterion of the total energy was set to 10e-6 eV in the self-consistent field loop. For structural relaxations, DFT-D3 correction was employed with BJ-damping to describe the dispersion forces and the convergence criterion of forces was set to 0.02 eV/Å. For band structure calculations, line sampling was employed to connecting high-symmetry points in the Brillouin zone as defined by AFLOW.