Exchange energy in the local Airy gas approximation

The Airy gas model of the edge electron gas is used to construct an exchange-energy functional that is an alternative to those obtained in the local-density and generalized-gradient approximations. Test calculations for rare-gas atoms, molecules, solids, and surfaces show that the Airy gas functional performs better than the local-density approximation in all cases and better than the generalized-gradient approximation for solids and surfaces.