Comment on the formation of He2-4Ig states

The state He-2(-) I-4(g) (1 sigma (2)(g)1 sigma (u)1 sigma (g)1 phi (u)) of Adamowicz and Pluta [Chem. Phys. Lett. 179 (1991) 517] is shown to be (1 s igma (2)(g)1 sigma (u)2 sigma (g)1 phi (u)). A variational calculation usin g one electron diatomic molecular orbitals, as well as a complete active sp ace self-consistent field calculation, predict it to be unbound with respec t to its neutral parent states. It is argued that He-2(-) I-4(g) (1 sigma ( 2)(g)1 sigma (u)1 delta (g)1 phi (u)) cannot exist. (C) 2000 Elsevier Scien ce B.V. All rights reserved.