For closed shells in a bare Coulomb field, the one-centre densityp(r) can be characterized solely by s states. Here, the two-centre bare Coulomb field is considered for the molecular ion H+2. The potential energy curve, known to be a unique function of the ground-state densityp(rR), withRthe internuclear separation, is shown here to be determined solely by the electron density on the plane perpendicularly bisecting the bond axis.