We consider the high-density-limit correlation energy \Ec in D≥2
dimensions for the 1S ground states of three two-electron systems: helium
(in which the electrons move in a Coulombic field), spherium (in which they
move on the surface of a sphere), and hookium (in which they move in a
quadratic potential). We find that the \Ec values are strikingly similar,
depending strongly on D but only weakly on the external potential. We
conjecture that, for large D, the limiting correlation energy \Ec \sim
-\delta^2/8 in any confining external potential, where δ=1/(D−1).Comment: 4 pages, 0 figur