Towards a universal exchange enhancement factor in density functional theory

A broadly used strategy to go beyond the well-known local-density approximation of density functional theory relies on the choice of a so-called exchange-correlation (xc) enhancement factor Fxc, defined as the enhancement of a realistic xc energy density over its local exchange-only counterpart. To date, this density functional, Fxc, has been constructed by following either semiempirical strategies or nonempirical schemes that impose the fulfillment of exact constraints. Here, we follow a totally different route, which is based on an attempt to construct a universal exchange enhancement factor Fx from the exact exchange energy density of a given family of electron density profiles and which we implement on the basis of jellium-slab exact-exchange self-consistent calculations. We find that such an enhancement factor can, indeed, be built which obeys, within our sample of electron-density profiles, most exact constraints and thus represents a benchmark towards the construction of a universal exchange enhancement factor suitable for all electron densities. We provide, in particular, an analytical parametrization of our ab initio calculations at the level of the generalized gradient approximation.

Automated summary

This study aims to improve the local-density approximation in density functional theory by constructing a universal exchange enhancement factor Fx. Through jellium-slab exact-exchange self-consistent calculations, we found that such an enhancement factor can be built which satisfies most exact constraints and can be applied to all electron densities.