Effect of the Gradient of the Spin Polarization in Density Functional Approximations

The construction of non-empirical density functional approximations is typically guided by the satisfaction of exact constraints. An important constraint is the recovery of the gradient expansion for slowly varying electron densities. In prior constructions of semilocal density functional approximations, the ∇ζ-dependent terms in the gradient expansion of the correlation have been dropped. In this talk, we propose a scheme by which such terms can be reintroduced into already constructed functionals without significantly affecting other constraints and norms. We implement this scheme on the Strongly Constrained and Appropriately Normed (SCAN) functional to construct a ∇ζ-corrected version of SCAN. The resulting functional has been shown to provide improvements in transition-metal atoms and molecules.