Importance of two-body correlations in the 4He molecules

We investigated whether the recently developed Integrodifferential Equation Approach to Few-and Many-body systems, known as IDEA, can be used to study the ground-state properties of He-molecules. Using two realistic He-4-He-4 interactions of Aziz and collaborators, the binding energies and the root mean-square radii for small molecules are calculated and the results obtained are compared with those previously obtained by other methods. The principal result of this study is that the practically hard-core and the short-range attraction of the molecular potentials give rise to strong many-body correlations and an increased importance of higher partial waves which cannot be, adequately, handled with S-wave projected formalisms.