title: On the possible "supersolid" character of parahydrogen clusters.
abstract: We present results of a theoretical study of structural and superfluid properties of parahydrogen (p-H(2)) clusters comprising 25, 26, and 27 molecules at low temperature. The microscopic model utilized here is based on the Silvera-Goldman pair potential. Numerical results are obtained by means of quantum Monte Carlo simulations, making use of the continuous-space worm algorithm. The clusters are superfluid in the low temperature limit, but display markedly different physical behaviors. For N = 25 and 27, superfluidity at low temperature arises as clusters melt, that is, become progressively liquid-like as a result of quantum effects. On the other hand, for N = 26, the cluster remains rigid and solid-like. We argue that the cluster (p-H(2))(26) can be regarded as a mesoscopic "supersolid". This physical picture is supported by results of simulations in which a single p-H(2) molecule in the cluster is isotopically substituted.
authors.affiliation: Max-Planck-Institut für Quantenoptik, Hans-Kopfermann-Strasse 1, D-85748, Garching, Germany.
authors.forename: Fabio
authors.initials: F
authors.lastname: Mezzacapo
authors.forename: Massimo
authors.initials: M
authors.lastname: Boninsegni