Energetics ofMnO2polymorphs in density functional theory

We report the energetics and properties of the $\ensuremath{\beta}, \ensuremath{\alpha}$, R, $\ensuremath{\gamma}, \ensuremath{\lambda}$, and $\ensuremath{\delta}$ polymorphs of $\mathrm{MnO}{}_{2}$ within density functional theory, comparing the performance of the recently introduced SCAN functional with that of conventional exchange-correlation functionals and experiment. We find that SCAN uniquely yields accurate formation energies and properties across all $\mathrm{MnO}{}_{2}$ polymorphs. We explain the superior performance of SCAN based on its satisfaction of all known constraints appropriate to a semilocal exchange-correlation functional and its accurate representation of all types of orbital overlap.