Direct approach to density functional theory: iterative treatment using a polynomial representation of the Heaviside step function operator

A new approach to density functional theory is presented. The ground state electronic density and energy of a many-electron system are obtained directly using a polynomial representation of the Heaviside step operator acting on a trial wavefunction. A radial coordinate extension of the distributed approximating functional (DAF) is developed to treat Coulomb singularities and cusps accurately. Examples of electronic structure for the He and Ne atomic systems are presented.