Phase coexistence of cluster crystals: beyond the Gibbs phase rule

Abstract

We report a study of the phase behavior of multiple-occupancy crystals through simulation. We argue that in order to reproduce the equilibrium behavior of such crystals it is essential to treat the number of lattice sites as a constraining thermodynamic variable. The resulting free-energy calculations thus differ considerably from schemes used for single-occupancy lattices. Using our approach, we obtain the phase diagram and the bulk modulus for a generalized exponential model that forms cluster crystals at high densities. We compare the simulation results with existing theoretical predictions. We also identify two types of density fluctuations that can lead to two sound modes and evaluate the corresponding elastic constants.

4 pages, 3 figures

References in corpus (2)

• Why do ultrasoft repulsive particles cluster and crystallize? Analytical results from density functional theory
• Diffusion and Relaxation Dynamics in Cluster Crystals

Cited by in corpus (6)

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• Hexatic phase and cluster crystals of two-dimensional GEM4 spheres
• Micellar Crystals in Solution from Molecular Dynamics Simulations
• Cluster Luttinger liquids and emergent supersymmetric conformal critical points in the one-dimensional soft-shoulder Hubbard model
• Demixing cascades in cluster crystals
• [N]pT ensemble and finite-size scaling study of the GEM-4 critical isostructural transition