ADIABATIC APPROXIMATION IN ATOMIC 3-BODY SYSTEMS

We investigate the reliability of the adiabatic approximation in the h yperspherical harmonics formalism. It has been applied to a number of two-electron systems, both compact and loosely bound, with the interac tion between the constituent particles being purely Coulombic. The res ults are compared with the exact ones obtained by solving the set of c oupled differential equations numerically. The accuracy of this approx imation for two-electron systems is compared with that for systems wit h nuclear interactions, and we find that the former is better. An expl anation has been provided for better agreement with Coulombic systems, particularly for noncompact ones.