5 O ct 2 00 4 Triatomic Molecular Systems and Three - body forces : The Ar 3 case

We performed bound state calculations to obtain the first few vibrational states for the Ar3 molecular system. The equations used are of Faddeev-type and are solved directly as threedimensional equations in configuration space, i.e. without resorting to an explicit partial wave decomposition. In addition to realistic pairwise interactions, we employ long range three-body forces. Our results are in good agreement with those obtained by other methods based on partial wave expansion and show a significant contribution of the three-body forces (>10%) to the binding energy and thus their inclusion is, in general, warranted in studying similar triatomic systems.