Phase diagram of the Gaussian-core model

S. Prestipino; F. Saija; P. V. Giaquinta

doi:10.1103/physreve.71.050102

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Phase diagram of the Gaussian-core model

S. Prestipino·F. Saija·P. V. Giaquinta

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Abstract

We trace with unprecedented 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.

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S. Prestipino, F. Saija, P. V. Giaquinta. 2005-06-01. Phase diagram of the Gaussian-core model. https://doi.org/10.1103/physreve.71.050102

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