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.

Combining Rare Events Techniques: Phase Change in Si Nanoparticles / Orlandini, Sergio; Meloni, Simone; Ciccotti, Giovanni. - In: JOURNAL OF STATISTICAL PHYSICS. - ISSN 0022-4715. - STAMPA. - 145:4(2011), pp. 812-830. [10.1007/s10955-011-0390-9]

Combining Rare Events Techniques: Phase Change in Si Nanoparticles

ORLANDINI, SERGIO;MELONI, Simone;CICCOTTI, Giovanni
2011

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.
2011
Order-disorder phase transition; Parallel Tempering; Rare events; Restrained MD; Si nanoparticles; Statistical and Nonlinear Physics; Mathematical Physics
01 Pubblicazione su rivista::01a Articolo in rivista
Combining Rare Events Techniques: Phase Change in Si Nanoparticles / Orlandini, Sergio; Meloni, Simone; Ciccotti, Giovanni. - In: JOURNAL OF STATISTICAL PHYSICS. - ISSN 0022-4715. - STAMPA. - 145:4(2011), pp. 812-830. [10.1007/s10955-011-0390-9]
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11573/950982
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