On the solvation structure of a raregas solute in superfluid helium-4

Path integral hybrid Monte Carlo calculations have been performed for a system consisting of a single neon atom in the superfluid helium. An expression of the local superfluid density around the solute atom is introduced to analyze the microscopic density fluctuation around the solute in detail. We show that the superfluid component in the solvation shell dramatically increases with lowering temperature, although the radial number density profile itself is almost independent of temperature. We also compare the local superfluid density calculated by our expression with that by another commonly used one. Although both local superfluid densities show similar trend as a function of the radial distance from the solute atom, quantitative differences are found; the superfluid component is underestimated by the commonly used one. This is due to the fact that the commonly used definition of the local superfluid density does not give the bulk superfluid density by integrating it over the whole space. The new expression introduced in the present study is free from such a deficiency.