Relevance of the Slowly Varying Electron Gas to Atoms, Molecules, and Solids
Relevance of the Slowly Varying Electron Gas to Atoms, Molecules, and Solids
We present a Thomas-Fermi-inspired density scaling under which electron densities of atomic, molecular, or condensed matter become both large and slowly varying, so that semiclassical approximations and second-order density gradient expansions are asymptotically exact for the kinetic and exchange energies. Thus, even for atoms and molecules, density-functional approximations should recover …