  The concept of correlation is central to all approaches that attempt the
description of many-body effects in electronic systems. Multipartite
correlation is a quantum information theoretical property that is attributed to
quantum states independent of the underlying physics. In quantum chemistry,
however, the correlation energy (the energy not seized by the Hartree-Fock
ansatz) plays a more prominent role. We show that these two different
viewpoints on electron correlation are closely related. The key ingredient
turns out to be the energy gap within the symmetry-adapted subspace. We then
use a few-site Hubbard model and the stretched H$_2$ to illustrate this
connection and to show how the corresponding measures of correlation compare.
