A General Minimum Principle for Correlated Densities in Quantum Many-Particle Systems

It is shown that interacting many-particle quantum systems can be described in terms of fully correlated {ital n}-particle densities, which determine uniquely the potential acting on the system and satisfy a minimum principle with respect to the ground-state energy. This leads to a generalization of ordinary density functional theory in terms of {ital n}-particle densities which allows the direct and self-consistent treatment of correlation effects within electronic structure methods for atoms, molecules, and solids. {copyright} {ital 1996 The American Physical Society.}