4He/H2 binary clusters:: A path-integral Monte Carlo study

The structure and thermodynamic properties of the He-4/H-2 binary clusters are studied by path-integral Monte Carlo simulations. It has been found that, despite their lower mass, the H-2 molecules form a subcluster of their own at the center of the system. When the number of helium atoms increases for a fixed number of hydrogen molecules, those inner clusters get compressed but retain their original form. The fraction of H-2 in the superfluid state decreases with the subcluster compression, but remains finite for small H-2 concentrations. [S0163-1829(99)01433-2].