IMPROVED LOCAL-DENSITY APPROXIMATION TO THE EXCHANGE AND KINETIC-ENERGY FUNCTIONALS FOR ATOMIC SYSTEMS

Through the derivation of a bound to the gradient correction for the e xchange energy, a new local density (LD) approximation to the exchange energy density functional and an analogous LD form for the kinetic en ergy density functional are proposed. Both these gradient-free functio nals valid for spherically symmetric electron densities, yield excelle nt results for exchange and kinetic energies, using Hartree-Fock atomi c densities.