[N]pT Monte Carlo simulations of the cluster-crystal-forming penetrable sphere model.

Journal Article (Journal Article)

Certain models with purely repulsive pair interactions can form cluster crystals with multiply-occupied lattice sites. Simulating these models' equilibrium properties is, however, quite challenging. Here, we develop an expanded isothermal-isobaric [N]pT ensemble that surmounts this problem by allowing both particle number and lattice spacing to fluctuate. It is particularly efficient at high T, where particle insertion is facile. Using this expanded ensemble and thermodynamic integration, we solve the phase diagram of a prototypical cluster-crystal former, the penetrable sphere model, and compare the results with earlier theoretical predictions. At high temperatures and densities, the equilibrium occupancy n(c)(eq) of face-centered cubic crystal increases linearly. At low temperatures, although n(c)(eq) plateaus at integer values, the crystal behavior changes continuously with density. The previously ambiguous crossover around T ~ 0.1 is resolved.

Full Text

Duke Authors

Cited Authors

  • Zhang, K; Charbonneau, P

Published Date

  • June 2012

Published In

Volume / Issue

  • 136 / 21

Start / End Page

  • 214106 -

PubMed ID

  • 22697529

Electronic International Standard Serial Number (EISSN)

  • 1089-7690

International Standard Serial Number (ISSN)

  • 0021-9606

Digital Object Identifier (DOI)

  • 10.1063/1.4723869


  • eng