title: Phase diagram of the Gaussian-core model.
abstract: We trace with high numerical accuracy the phase diagram of the Gaussian-core model, a classical system of point particles interacting via a Gaussian-shaped, purely repulsive potential. This model, which provides a reliable qualitative description of the thermal behavior of interpenetrable globular polymers, is known to exhibit a polymorphic fcc-bcc transition at low densities and reentrant melting at high densities. Extensive Monte Carlo simulations, carried out in conjunction with accurate calculations of the solid free energies, lead to a thermodynamic scenario that is partially modified with respect to previous knowledge. In particular, we find that: (i) the fluid-bcc-fcc triple-point temperature is about one third of the maximum freezing temperature; (ii) upon isothermal compression, the model exhibits a fluid-bcc-fcc-bcc-fluid sequence of phases in a narrow range of temperatures just above the triple point. We discuss these results in relation to the behavior of star-polymer solutions and of other softly repulsive systems.
authors.affiliation: Dipartimento di Fisica, Università degli Studi di Messina, Contrada Papardo, 98166 Messina, Italy. Santi.Prestipino@unime.it
authors.forename: Santi
authors.initials: S
authors.lastname: Prestipino
authors.forename: Franz
authors.initials: F
authors.lastname: Saija
authors.forename: Paolo V
authors.initials: PV
authors.lastname: Giaquinta