Attachment energetics of quantum dopants in a weakly interacting quantum solvent: 1H, 2H and 3H in small 4He clusters

Small (4)He clusters doped with a single atomic impurity, (1)H, (2)H, and (3)H, have been studied via a quantum Monte Carlo approach with the intent of establishing their binding behavior in nanoscopic clusters. Our calculations find that the only trimer (x)H (He)(2), which exhibits a bound state, is that with the tritium dopant (x = 3), in agreement with previous calculations using hyperspherical coordinates in the adiabatic approximation. The lightest dopant (1)H is seen not to stabilize the small helium clusters, while (2)H and (3)H are weakly bound to this solvent: our computed exchange energies and probability distribution functions reveal the "heliophobic" nature of hydrogen, leading thus to a further confirmation, in the realm of nanoscopic-size systems like the helium droplets, of the well-known nonmixing and nonsolvating features of hydrogen in macroscopic liquid bulk helium.