Eur. Phys. J. B 53, 47-60 (2006)
https://doi.org/10.1140/epjb/e2006-00353-0

Free energy landscape from path-sampling: application to the structural transition in LJ₃₈

¹ Service de Recherches de Métallurgie Physique, Commissariat à l'Énergie Atomique/Saclay, 91191 Gif-sur-Yvette, France
² Laboratoire de Chimie et Physique Quantiques, IRSAMC, Université Paul Sabatier, 118 route de Narbonne, 31062 Toulouse Cedex, France

Corresponding author: ^a Manuel.Athenes@cea.fr

Received: 31 May 2006
Revised: 27 July 2006
Published online: 22 September 2006

Abstract

We introduce a path-sampling scheme that allows equilibrium state-ensemble averages to be computed by means of a biased distribution of non-equilibrium paths. This non-equilibrium method is applied to the case of the 38-atom Lennard-Jones atomic cluster, which has a double-funnel energy landscape. We calculate the free energy profile along the Q₄ bond orientational order parameter. At high or moderate temperature the results obtained using the non-equilibrium approach are consistent with those obtained using conventional equilibrium methods, including parallel tempering and Wang-Landau Monte Carlo simulations. At lower temperatures, the non-equilibrium approach becomes more efficient in exploring the relevant inherent structures. In particular, the free energy agrees with the predictions of the harmonic superposition approximation.