THE STRUCTURE OF THE ATOMIC HELIUM TRIMERS - HALOS AND EFIMOV STATES

The Faddeev equations for the atomic helium-trimer systems are solved numerically with high accuracy both for the most sophisticated realist ic potentials available and for simple phenomenological potentials. An efficient numerical procedure is described. The large distance asympt otic behaviour, crucial for weakly bound three-body systems, is descri bed almost analytically for arbitrary potentials. The Efimov effect is especially considered. The geometric structures of the bound states a re quantitatively investigated. The accuracy of the schematic models a nd previous computations is comparable, i.e. within 20% for the spatia lly extended states and within 40% for the smaller He-4-trimer ground state.