On the Possibility of Binding of Two Electrons to Dipole Potentials

Ž . ABSTRACT: The possibility of binding two electrons by the fixed finite dipole FFD potential due to two point charges qqe and yqe separated by the distance R is explored at the full configuration interaction level with extended basis sets. The critical value of the dipole moment m s qR required to bind two electrons tends to infinity for small q Ž . Ž q f 0.91e and decreases precipitously as q increases. In the limit of very large q and . Ž . small R , this critical dipole moment seems to approach a limit below 2 Debyes D . It is shown analytically that in the point dipole limit this critical dipole value will approach that for binding a single electron. An extension of the FFD model to include effects of y y y Ž . inner-shell core electrons allows the Li , Na , and K cases with a y1e charge at R Ž also to be examined. FFD-plus-core systems display even larger critical dipoles 113, . Ž . 129, and 141 D, respectively than does the qqeryqe FFD potential 92.2 D . These Ž findings suggest that it will be difficult to find a real molecule that can bind by y1. f 1 cm two electrons via its dipole potential. Finally, a simple electrostatic model is introduced which permits the critical dipole value of the FDD and its core]orbital extension to be evaluated rather well. Q 2000 John Wiley & Sons, Inc. Int J Quant Chem 76: 197]204, 2000