Abstract
Approximate expressions for the Coulomb U and exchange-correlation Exc energies in LDF theory for molecules and atomic clusters are discussed. Evaluating U using a constrained fit to the charge density leads to terms in the potential, derived from U, not discussed by previous workers. A method is described of evaluating Exc which is fast and requires only a fit to the charge density. Results of self-consistent pseudopotential calculations are given for the molecules C2 and H2O.