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Free-energy Calculations Using Classical Molecular Simulation: Application to the Determination of the Melting Point and Chemical Potential of a Flexible RDX Model.
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SYSNO ASEP 0461336 Document Type J - Journal Article R&D Document Type Journal Article Subsidiary J Článek ve WOS Title Free-energy Calculations Using Classical Molecular Simulation: Application to the Determination of the Melting Point and Chemical Potential of a Flexible RDX Model. Author(s) Sellers, M.S. (US)
Lísal, Martin (UCHP-M) RID, ORCID, SAI
Brennan, J.K. (US)Source Title Physical Chemistry Chemical Physics. - : Royal Society of Chemistry - ISSN 1463-9076
Roč. 18, č. 11 (2016), s. 7841-7850Number of pages 11 s. Language eng - English Country GB - United Kingdom Keywords solid-liquid coexistence ; atomistic simulation ; dynamics simulations Subject RIV CF - Physical ; Theoretical Chemistry R&D Projects GA13-02938S GA ČR - Czech Science Foundation (CSF) Institutional support UCHP-M - RVO:67985858 UT WOS 000372229700028 EID SCOPUS 84960935550 DOI 10.1039/c5cp06164d Annotation We present an extension of various free-energy methodologies to determine the chemical potential of the solid and liquid phases of a fully-flexible molecule using classical simulation. The methods are applied to the Smith-Bharadwaj atomistic potential representation of cyclotrimethylene trinitramine (RDX), a well-studied energetic material, to accurately determine the solid and liquid phase Gibbs free energies, and the melting point (T-m). We outline an efficient technique to find the absolute chemical potential and melting point of a fully-flexible molecule using one set of simulations to compute the solid absolute chemical potential and one set of simulations to compute the solid-liquid free energy difference. With this combination, only a handful of simulations are needed, whereby the absolute quantities of the chemical potentials are obtained, for use in other property calculations, such as the characterization of crystal polymorphs or the determination of the entropy. Using the LAMMPS molecular simulator, the Frenkel and Ladd and pseudo-supercritical path techniques are adapted to generate 3rd order fits of the solid and liquid chemical potentials. Results yield the thermodynamic melting point T-m = 488.75 K at 1.0 atm. We also validate these calculations and compare this melting point to one obtained from a typical superheated simulation technique. Workplace Institute of Chemical Process Fundamentals Contact Eva Jirsová, jirsova@icpf.cas.cz, Tel.: 220 390 227 Year of Publishing 2017
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