Journal of Statistical Physics

, Volume 145, Issue 4, pp 812–830

Combining Rare Events Techniques: Phase Change in Si Nanoparticles

  • Sergio Orlandini
  • Simone Meloni
  • Giovanni Ciccotti
Article

DOI: 10.1007/s10955-011-0390-9

Cite this article as:
Orlandini, S., Meloni, S. & Ciccotti, G. J Stat Phys (2011) 145: 812. doi:10.1007/s10955-011-0390-9

Abstract

We describe a combined Restrained MD/Parallel Tempering approach to study the difference in free energy as a function of a set of collective variables between two states in presence of metastabilities in the manifold orthogonal to the one spanned by the chosen collective variables. We illustrate the method by an extended study of the relative stability of the amorphous vs crystalline Si nanoparticles embedded in a-SiO2 of size ranging between 0.8 and 1.8 nm as a function of temperature [S. Orlandini, S. Meloni, and L. Colombo in Phys. Rev. B 83:235303, 2011]. The results show that the method permits to get over the hidden metastabilities. Finally, we try to identify the missing collective variables from the Restrained MD/Parallel Tempering trajectories and analyze whether the collective variable used to control the amorphous-to-crystalline transition is adequate to describe the mechanism of crystallization of some of the nanoparticles considered.

Keywords

Rare eventsRestrained MDParallel TemperingSi nanoparticlesOrder-disorder phase transition

Copyright information

© Springer Science+Business Media, LLC 2011

Authors and Affiliations

  • Sergio Orlandini
    • 2
    • 3
  • Simone Meloni
    • 1
    • 2
  • Giovanni Ciccotti
    • 1
    • 4
  1. 1.School of PhysicsUniversity College DublinDublin 4Ireland
  2. 2.Consorzio Interuniversitario per le Applicazioni di Supercalcolo Per Università e Ricerca (CASPUR)RomeItaly
  3. 3.Dipartimento di ChimicaUniversità “Sapienza”RomeItaly
  4. 4.Dipartimento di Fisica and CNISMUniversità “Sapienza”RomeItaly