Continuous thermodynamic integration in field-theoretic simulations of structured polymers

Spencer, Russell K. W. and Vorselaars, Bart and Matsen, Mark W. (2017) Continuous thermodynamic integration in field-theoretic simulations of structured polymers. Macromolecular Theory and Simulations, 26 (5). p. 1700036. ISSN 1022-1344

Full content URL: http://dx.doi.org/10.1002/mats.201700036

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Abstract

This work explores the use of continuous thermodynamic integration in field-theoretic simulations of a symmetric diblock copolymer melt. Free energies of the lamellar and disorder phases are evaluated by thermodynamic integration from a reference state (an Einstein crystal, λ = 0) to a diblock copolymer (λ = 1). This is followed by integration over the interaction parameter, χb, to locate the order–disorder transition (ODT). Then the equilibrium lamellar spacing and free energy cost of stretching and compressing lamellae are examined. The ODT, lamellar spacing, and compression modulus are consistent with previous calculations, though found faster and more precisely. The above quantities do not depend on simulation box size, suggesting that finite-size effects are small and simulating two lamellar periods is sufficient to accurately evaluate bulk behavior. Furthermore, the statistical uncertainty in the ODT increases quickly with system size, suggesting that small systems may lead to more precise results.

Keywords:Diblock copolymer, Phase behavior, thermodynamic integration, finite-size effects, field theoretic simulations
Subjects:F Physical Sciences > F200 Materials Science
G Mathematical and Computer Sciences > G330 Stochastic Processes
F Physical Sciences > F300 Physics
F Physical Sciences > F162 Polymer Chemistry
F Physical Sciences > F343 Computational Physics
Divisions:College of Science > School of Mathematics and Physics
ID Code:28106
Deposited On:04 Aug 2017 09:56

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