Elasticity of flexible and semiflexible polymers with extensible bonds in the Gibbs and Helmholtz ensembles

Stretching experiments on single molecules of arbitrary length opened the way for studying the statistical mechanics of small systems. In many cases in which the thermodynamic limit is not satisfied, different macroscopic boundary conditions, corresponding to different statistical mechanics ensemble...

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Bibliographic Details
Published in:The Journal of chemical physics 2012-04, Vol.136 (15), p.154906-154906-10
Main Authors: Manca, Fabio, Giordano, Stefano, Palla, Pier Luca, Zucca, Rinaldo, Cleri, Fabrizio, Colombo, Luciano
Format: Article
Language:English
Subjects:
Chains (polymeric)
Computer simulation
Elasticity
Extensibility
Monte Carlo Method
Monte Carlo methods
Polymers
Polymers - chemistry
Statistical mechanics
Thermodynamics
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Summary:Stretching experiments on single molecules of arbitrary length opened the way for studying the statistical mechanics of small systems. In many cases in which the thermodynamic limit is not satisfied, different macroscopic boundary conditions, corresponding to different statistical mechanics ensembles, yield different force-displacement curves. We formulate analytical expressions and develop Monte Carlo simulations to quantitatively evaluate the difference between the Helmholtz and the Gibbs ensembles for a wide range of polymer models of biological relevance. We consider generalizations of the freely jointed chain and of the worm-like chain models with extensible bonds. In all cases we show that the convergence to the thermodynamic limit upon increasing contour length is described by a suitable power law and a specific scaling exponent, characteristic of each model.
ISSN:0021-9606
1089-7690
DOI:10.1063/1.4704607