Electron correlation and the eigenvalues of the one-matrix

The Jaynes entropy of the one-particle reduced density matrix is examined within the context of the convex set of N-representable one-matrices. The monotonic relationship of the Jaynes entropy with distance from the hull of the convex set is highlighted, and we show that the Jaynes entropy is monotonically related to the density-functional definition of the correlation energy, thus qualifying a conjecture of Collins which assumed a simple proportionality. It is further suggested that maximization of the Jaynes entropy subject to the constraints of fixed density and kinetic energy picks out the true one-matrix