Deorbitalization of meta-GGA exchange correlation functionals*

We explore the simplification of widely used meta-generalized-gradient approximation (meta-GGA) exchange-correlation functionals to the Laplacian level of refinement by use of approximate kinetic energy density functionals (KEDFs). Such deorbitalization is motivated by the prospect of reducing computational cost while recovering a strictly Kohn-Sham local potential framework (rather than the usual generalized Kohn-Sham treatment of meta-GGAs). Rather good results on standard molecular and condensed-phase test sets are obtained from the deorbitalized version of the SCAN functional.
The existence of deorbitalizations which yield better performance than the original meta-GGA is illustrated for molecules with the meta-GGA made very simple functional.