Ab initioapproach for many-electron systems without invoking orbitals: An integral formulation of density-functional theory

A new approach for the calculation of ground states of many-electron systems is developed via an integral formulation of the Hohenberg-Kohn-Sham density-functional theory. Orbitals are not employed. In place of the set of one-electron equations, the total electron density is explicitly expressed in terms of the Kohn-Sham local potential through a multidimensional integration. This offers the possibility of ab initio calculations for molecules with very many electrons. The method can also be applied to calculate Compton profiles.