Superfluidity of helium-4 around a Mg11 cluster

We present results for He-4 solvation of a Mg-11 cluster obtained with path integral Monte Carlo simulations. Using a pair-wise additive model for the helium-cluster interaction, we calculate energies, He-4 densities and the superfluid response of He-4 to a rotation of the Mg-11 cluster which has symmetric top symmetry. We find a significant superfluid fraction in the first He-4 solvation layer around both axes of the cluster well before He-4 covers the whole cluster. Based on the superfluid fraction, we estimate that Mg-11 in a large He-4 nanodroplet would have an effective rotational constant between 60% and 70% of the gas phase rotational constant for rotation about the axis with larger moment of inertia. The dependence of the effective rotational constants on He-4 cluster size N is similar to that of previously studied molecules with much larger gas phase rotational constants, with an initial decrease and a turn-around (at N = 13) when part of the He-4 density becomes superfluid.