Density-Corrected SCAN Meta-GGA**

The strongly constrained and appropriately normed (SCAN) [1] meta-generalized gradient approximation satisfies 17 exact constaints on the density functional for the exchange-correlaton energy, and works well on its own self-consistent density for many atoms, molecules, and condensed phases. But density-corrected [2] SCAN, which evaluates SCAN on a "better" density such as that of Hartree-Fock theory, is often more accurate, and strikingly so for energy barriers [3] and for water clusters and liquid water [4]. For water, the accuracy of density-corrected SCAN approaches that of coupled cluster theory. The likely reason for this is that Hartree-Fock theory more correctly tends to localize an integer electron number within each system fragment, while computationally-efficient density functionals may not [5].

[1] J. Sun. A. Ruzsinszky, and J.P. Perdew, Phys. Rev. Lett. 115, 036402 (2015).

[2] M.-C. Kim, E. Sim, and K. Burke, Phys. Rev. Lett. 111, 073003 (2013).

[3] G. Santra and J.A. Martin, J. Chem. Theory Comput. 17, 1368 (2021).

[4] S. Dasgupta, E. Lambros, J.P. Perdew, and F. Paesani, Nature Commun., to appear. 

[5] J.P. Perdew, R.G. Parr, M. Levy, and J.L. Balduz, Phys. Rev. Lett. 49, 1691 (1982).