Superfluidity and structural order in H4e adsorbed on a C20 molecule: Path-integral Monte Carlo calculations
Abstract
We have studied adsorption of H4e on the surface of a single C20 fullerene molecule using the path-integral Monte Carlo method. For a full incorporation of the surface corrugations on the molecular surface the H4e-C20 interaction is treated with a sum of empirical helium-carbon interatomic pair potentials. Radial density distributions show layer-by-layer growth of H4e , and a detailed analysis of energetics and angular density distributions reveals that the strongly bound first layer, located at a distance of ∼4.9Å from the center of the C20 molecule, is in various quantum states as the number of H4e atoms changes. This layer, when completed with 32 atoms, is found to be a solid whose structure is commensurate with the underlying molecular surface. Near the completion of the first layer we observe a finite superfluid fraction as well as a solid order at a low temperature of T=0.31K . This manifestation of supersolidity on a nanometer scale is understood to be induced by the presence of mobile vacancies.
- Publication:
-
Physical Review B
- Pub Date:
- November 2010
- DOI:
- Bibcode:
- 2010PhRvB..82q2506K
- Keywords:
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- 67.80.bd;
- 67.25.dw;
- 05.30.Jp;
- 61.48.-c;
- Superfluidity in solid <sup>4</sup>He supersolid <sup>4</sup>He;
- Superfluidity in small clusters;
- Boson systems;
- Structure of fullerenes and related hollow molecular clusters