Asymptotic properties of two-particle and single-particle density matrices in N-electron atoms and molecules

The asymptotic form of the single-particle density matrix in an N-electron atom is known to be determined by the overlap of the ground state wave functions of the N and (N−1) electron systems. We discuss the generalization of this result to the two particle density matrix. The connection with recent work by Patil on the asymptotic form of the wave function for two-electron atomic ions, and its generalization, is pointed out.