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Interfacial Forces in Free-Standing Layers of Melted Polyethylene, from Critical to Nanoscopic Thicknesses. Polymers (Basel) 2022; 14:polym14183865. [PMID: 36146008 PMCID: PMC9503058 DOI: 10.3390/polym14183865] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2022] [Revised: 09/04/2022] [Accepted: 09/07/2022] [Indexed: 11/17/2022] Open
Abstract
Molecular dynamics simulations of ultrathin free-standing layers made of melted (373.15–673.15 K) polyethylene chains, which exhibit a lower melting temperature (compared to the bulk value), were carried out to investigate the dominant pressure forces that shape the conformation of chains at the interfacial and bulk liquid regions. We investigated layer thicknesses, tL, from the critical limit of mechanical stability up to lengths of tens of nm and found a normal distribution of bonds dominated by slightly stretched chains across the entire layer, even at large temperatures. In the bulk region, the contribution of bond vibrations to pressure was one order of magnitude larger than the contributions from interchain interactions, which changed from cohesive to noncohesive at larger temperatures just at a transition temperature that was found to be close to the experimentally derived onset temperature for thermal stability. The interchain interactions produced noncohesive interfacial regions at all temperatures in both directions (normal and lateral to the surface layer). Predictions for the value of the surface tension, γ, were consistent with experimental results and were independent of tL. However, the real interfacial thickness—measured from the outermost part of the interface up to the point where γ reached its maximum value—was found to be dependent on tL, located at a distance of 62 Å from the Gibbs dividing surface in the largest layer studied (1568 chains or 313,600 bins); this was ~4 times the length of the interfacial thickness measured in the density profiles.
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2
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Kaur J, Deb D. Interfacial stiffness of nematic-smectic B interface in Gay-Berne liquid crystals using capillary wave theory. J Chem Phys 2021; 155:044901. [PMID: 34340369 DOI: 10.1063/5.0049498] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
The interfacial stiffness for nematic-smectic B (nm-smB) interface in a liquid crystalline (LC) material is calculated using Capillary Wave Theory (CWT) and molecular dynamics simulations. The Gay-Berne (GB) pair potential with parameters κ, κ', μ, and ν equal to 3, 5, 2, and 1 is used to model the LC material. Using a smart three-step recipe, we have obtained an nm-smB phase coexistence in our simulations where the nm and smB directors are nearly parallel to each other and perpendicular to the interface normal. The density profiles are used to compute the nm-smB coexisting density range, the interfacial width, and its position. The smectic phase is differentiated from the nematic phase by using the local bond order parameter (q6q6), which has helped us to demonstrate that the interface is indeed rough. Finally, the interfacial stiffness of the nm-smB interface is computed by following the CWT analysis and is found to be γ̃nm-smB=0.39861kBT/σee 2=0.04429/σss 2, where σee and σss are the length and diameter of the GB LC particles.
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Affiliation(s)
- Jagroop Kaur
- School of Physics and Materials Science, Thapar Institute of Engineering and Technology, Bhadson Road, Patiala, Punjab 147004, India
| | - Debabrata Deb
- School of Physics and Materials Science, Thapar Institute of Engineering and Technology, Bhadson Road, Patiala, Punjab 147004, India
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3
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Tang F, Ohto T, Sun S, Rouxel JR, Imoto S, Backus EHG, Mukamel S, Bonn M, Nagata Y. Molecular Structure and Modeling of Water-Air and Ice-Air Interfaces Monitored by Sum-Frequency Generation. Chem Rev 2020; 120:3633-3667. [PMID: 32141737 PMCID: PMC7181271 DOI: 10.1021/acs.chemrev.9b00512] [Citation(s) in RCA: 83] [Impact Index Per Article: 20.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2019] [Indexed: 12/26/2022]
Abstract
From a glass of water to glaciers in Antarctica, water-air and ice-air interfaces are abundant on Earth. Molecular-level structure and dynamics at these interfaces are key for understanding many chemical/physical/atmospheric processes including the slipperiness of ice surfaces, the surface tension of water, and evaporation/sublimation of water. Sum-frequency generation (SFG) spectroscopy is a powerful tool to probe the molecular-level structure of these interfaces because SFG can specifically probe the topmost interfacial water molecules separately from the bulk and is sensitive to molecular conformation. Nevertheless, experimental SFG has several limitations. For example, SFG cannot provide information on the depth of the interface and how the orientation of the molecules varies with distance from the surface. By combining the SFG spectroscopy with simulation techniques, one can directly compare the experimental data with the simulated SFG spectra, allowing us to unveil the molecular-level structure of water-air and ice-air interfaces. Here, we present an overview of the different simulation protocols available for SFG spectra calculations. We systematically compare the SFG spectra computed with different approaches, revealing the advantages and disadvantages of the different methods. Furthermore, we account for the findings through combined SFG experiments and simulations and provide future challenges for SFG experiments and simulations at different aqueous interfaces.
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Affiliation(s)
- Fujie Tang
- Max
Planck Institute for Polymer Research, Ackermannweg 10, Mainz 55128, Germany
- Department
of Physics, Temple University, Philadelphia, Pennsylvania 19122, United States
| | - Tatsuhiko Ohto
- Graduate
School of Engineering Science, Osaka University, 1-3 Machikaneyama, Toyonaka, Osaka 560-8531, Japan
| | - Shumei Sun
- Max
Planck Institute for Polymer Research, Ackermannweg 10, Mainz 55128, Germany
- Department
of Physical Chemistry, University of Vienna, Währinger Strasse 42, 1090 Vienna, Austria
| | - Jérémy R. Rouxel
- Department
of Chemistry and Department of Physics and Astronomy, University of California, Irvine, Irvine, California 92697-2025, United States
| | - Sho Imoto
- Max
Planck Institute for Polymer Research, Ackermannweg 10, Mainz 55128, Germany
| | - Ellen H. G. Backus
- Max
Planck Institute for Polymer Research, Ackermannweg 10, Mainz 55128, Germany
- Department
of Physical Chemistry, University of Vienna, Währinger Strasse 42, 1090 Vienna, Austria
| | - Shaul Mukamel
- Department
of Chemistry and Department of Physics and Astronomy, University of California, Irvine, Irvine, California 92697-2025, United States
| | - Mischa Bonn
- Max
Planck Institute for Polymer Research, Ackermannweg 10, Mainz 55128, Germany
| | - Yuki Nagata
- Max
Planck Institute for Polymer Research, Ackermannweg 10, Mainz 55128, Germany
- Department
of Physics, State Key Laboratory of Surface Physics and Key Laboratory
of Micro- and Nano-Photonic Structures (MOE), Fudan University, Shanghai 200433, China
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4
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Campo M, Speck T. Dynamical coexistence in moderately polydisperse hard-sphere glasses. J Chem Phys 2020; 152:014501. [DOI: 10.1063/1.5134842] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- Matteo Campo
- Institut für Physik, Johannes Gutenberg-Universität Mainz, Staudingerweg 7-9, 55128 Mainz, Germany
| | - Thomas Speck
- Institut für Physik, Johannes Gutenberg-Universität Mainz, Staudingerweg 7-9, 55128 Mainz, Germany
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5
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Rivera JL, Douglas JF. Reducing uncertainty in simulation estimates of the surface tension through a two-scale finite-size analysis: thicker is better. RSC Adv 2019; 9:35803-35812. [PMID: 35528077 PMCID: PMC9074429 DOI: 10.1039/c9ra07058c] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2019] [Accepted: 10/29/2019] [Indexed: 12/21/2022] Open
Abstract
Recent simulation studies of the surface tension γ, and other properties of thin free-standing films, have revealed unexpected finite size effects in which the variance of the properties vary monotonically with the in-plane width of the films, complicating the extrapolation of estimates of film properties to the thermodynamic limit. We carried out molecular dynamics simulations to determine the origin of this phenomenon, and to address the practical problem of developing a more reliable methodology for estimating γ in the thermodynamic limit. We find that there are two distinct finite size effects that must be addressed in a finite size analysis of γ in thin films. The first finite size scale is the in-plane width of the films and the second scale is the simulation cell size in the transverse direction. Increasing the first scale enhances fluctuations in γ, measured by the standard deviation of their distribution, while increasing the second reduces γ fluctuations due to a corresponding increased 'freedom' of the film to fluctuate out of plane. We find that using progressively large simulation cells in the transverse direction, while keeping the film width fixed to an extent in which the full bulk liquid zone is developed, allows us to obtain a smooth extrapolation to the thermodynamic limit, enabling a reduction of the γ uncertainty to a magnitude on the order of 1% for systems having a reasonably large size, i.e., O (1 μm).
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Affiliation(s)
- José L Rivera
- Laboratorio de Modelamiento y Simulación Molecular, Universidad Michoacana de San Nicolás de Hidalgo Morelia Michoacán 58000 Mexico
| | - Jack F Douglas
- Materials Science and Engineering Division, National Institute of Standards and Technology Gaithersburg Maryland 20899 USA
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6
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Sun S, Tang F, Imoto S, Moberg DR, Ohto T, Paesani F, Bonn M, Backus EHG, Nagata Y. Orientational Distribution of Free O-H Groups of Interfacial Water is Exponential. PHYSICAL REVIEW LETTERS 2018; 121:246101. [PMID: 30608741 DOI: 10.1103/physrevlett.121.246101] [Citation(s) in RCA: 43] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/30/2018] [Revised: 11/09/2018] [Indexed: 06/09/2023]
Abstract
The orientational distribution of free O-H (O-D) groups at the H_{2}O- (D_{2}O-)air interface is investigated using combined molecular dynamics (MD) simulations and sum-frequency generation (SFG) experiments. The average angle of the free O-H groups, relative to the surface normal, is found to be ∼63°, substantially larger than previous estimates of 30°-40°. This discrepancy can be traced to erroneously assumed Gaussian or stepwise orientational distributions of free O-H groups. Instead, the MD simulation and SFG measurement reveal a broad and exponentially decaying orientational distribution. The broad orientational distribution indicates the presence of the free O-H group pointing down to the bulk. We ascribe the origin of such free O-H groups to the presence of capillary waves on the water surface.
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Affiliation(s)
- Shumei Sun
- Max Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz, Germany
| | - Fujie Tang
- Max Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz, Germany
- International Center for Quantum Materials, School of Physics, Peking University, 5 Yiheyuan Road, Haidian, Beijing 100871, China
| | - Sho Imoto
- Max Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz, Germany
| | - Daniel R Moberg
- Department of Chemistry and Biochemistry, University of California, San Diego, La Jolla, California 92093, USA
| | - Tatsuhiko Ohto
- Graduate School of Engineering Science, Osaka University, 1-3 Machikaneyama, Toyonaka, Osaka 560-8531, Japan
| | - Francesco Paesani
- Department of Chemistry and Biochemistry, University of California, San Diego, La Jolla, California 92093, USA
| | - Mischa Bonn
- Max Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz, Germany
| | - Ellen H G Backus
- Max Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz, Germany
| | - Yuki Nagata
- Max Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz, Germany
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7
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Ohto T, Dodia M, Imoto S, Nagata Y. Structure and Dynamics of Water at the Water–Air Interface Using First-Principles Molecular Dynamics Simulations within Generalized Gradient Approximation. J Chem Theory Comput 2018; 15:595-602. [DOI: 10.1021/acs.jctc.8b00567] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Tatsuhiko Ohto
- Graduate School of Engineering Science, Osaka University, 1-3 Machikaneyama, Toyonaka, Osaka 560-8531, Japan
| | - Mayank Dodia
- Max Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz, Germany
| | - Sho Imoto
- Max Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz, Germany
| | - Yuki Nagata
- Max Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz, Germany
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8
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Horsley EM, Lavrentovich MO, Kamien RD. Aspects of nucleation on curved and flat surfaces. J Chem Phys 2018; 148:234701. [PMID: 29935505 DOI: 10.1063/1.5030752] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
We investigate the energetics of droplets sourced by the thermal fluctuations in a system undergoing a first-order transition. In particular, we confine our studies to two dimensions with explicit calculations in the plane and on the sphere. Using an isoperimetric inequality from the differential geometry literature and a theorem on the inequality's saturation, we show how geometry informs the critical droplet size and shape. This inequality establishes a "mean field" result for nucleated droplets. We then study the effects of fluctuations on the interfaces of droplets in two dimensions, treating the droplet interface as a fluctuating line. We emphasize that care is needed in deriving the line curvature energy from the Landau-Ginzburg energy functional and in interpreting the scalings of the nucleation rate with the size of the droplet. We end with a comparison of nucleation in the plane and on a sphere.
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Affiliation(s)
- Eric M Horsley
- Department of Physics and Astronomy, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA
| | - Maxim O Lavrentovich
- Department of Physics and Astronomy, University of Tennessee, Knoxville, Tennessee 37996, USA
| | - Randall D Kamien
- Department of Physics and Astronomy, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA
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9
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Richard D, Speck T. Crystallization of hard spheres revisited. II. Thermodynamic modeling, nucleation work, and the surface of tension. J Chem Phys 2018; 148:224102. [DOI: 10.1063/1.5025394] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- David Richard
- Institut für Physik, Johannes Gutenberg-Universität Mainz, Staudingerweg 7-9, 55128 Mainz, Germany
| | - Thomas Speck
- Institut für Physik, Johannes Gutenberg-Universität Mainz, Staudingerweg 7-9, 55128 Mainz, Germany
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10
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Longford FGJ, Essex JW, Skylaris CK, Frey JG. Unexpected finite size effects in interfacial systems: Why bigger is not always better-Increase in uncertainty of surface tension with bulk phase width. J Chem Phys 2018; 148:214704. [PMID: 29884027 DOI: 10.1063/1.5025887] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
We present an unexpected finite size effect affecting interfacial molecular simulations that is proportional to the width-to-surface-area ratio of the bulk phase Ll/A. This finite size effect has a significant impact on the variance of surface tension values calculated using the virial summation method. A theoretical derivation of the origin of the effect is proposed, giving a new insight into the importance of optimising system dimensions in interfacial simulations. We demonstrate the consequences of this finite size effect via a new way to estimate the surface energetic and entropic properties of simulated air-liquid interfaces. Our method is based on macroscopic thermodynamic theory and involves comparing the internal energies of systems with varying dimensions. We present the testing of these methods using simulations of the TIP4P/2005 water forcefield and a Lennard-Jones fluid model of argon. Finally, we provide suggestions of additional situations, in which this finite size effect is expected to be significant, as well as possible ways to avoid its impact.
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Affiliation(s)
| | | | | | - Jeremy G Frey
- University of Southampton, Southampton SO17 1BJ, United Kingdom
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11
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Tröster A, Schmitz F, Virnau P, Binder K. Equilibrium between a Droplet and Surrounding Vapor: A Discussion of Finite Size Effects. J Phys Chem B 2017; 122:3407-3417. [DOI: 10.1021/acs.jpcb.7b10392] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Andreas Tröster
- Institute of Materials Chemistry, Vienna University of Technology, Getreidemarkt 9, A-1060 Wien, Austria
| | - Fabian Schmitz
- Institut für Physik, Johannes Gutenberg-Universität Mainz, Staudinger Weg 9, D-55099 Mainz, Germany
| | - Peter Virnau
- Institut für Physik, Johannes Gutenberg-Universität Mainz, Staudinger Weg 9, D-55099 Mainz, Germany
| | - Kurt Binder
- Institut für Physik, Johannes Gutenberg-Universität Mainz, Staudinger Weg 9, D-55099 Mainz, Germany
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12
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Brumby PE, Wensink HH, Haslam AJ, Jackson G. Structure and Interfacial Tension of a Hard-Rod Fluid in Planar Confinement. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2017; 33:11754-11770. [PMID: 28885848 DOI: 10.1021/acs.langmuir.7b02254] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
The structural properties and interfacial tension of a fluid of rodlike hard-spherocylinder particles in contact with hard structureless flat walls are studied by means of Monte Carlo simulation. The calculated surface tension between the rod fluid and the substrate is characterized by a nonmonotonic trend as a function of the bulk concentration (density) over the range of isotropic bulk concentrations. As suggested by earlier theoretical studies, a surface-ordering scenario is confirmed by our simulations: the local orientational order close to the wall changes from uniaxial to biaxial nematic when the bulk concentration reaches about 85% of the value at the onset of the isotropic-nematic phase transition. The surface ordering coincides with a wetting transition whereby the hard wall is wetted by a nematic film. Accurate values of the fluid-solid surface tension, the adsorption, and the average particle-wall contact distance are reported (over a broad range of densities into the dense nematic region for the first time), which can serve as a useful benchmark for future theoretical and experimental studies on confined rod fluids. The simulation data are supplemented with predictions from second-virial density functional theory, which are in good qualitative agreement with the simulation results.
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Affiliation(s)
- Paul E Brumby
- Department of Mechanical Engineering, Keio University , 3-14-1 Hiyoshi, Kohoku-ku, Yokohama 223-8522, Japan
| | - Henricus H Wensink
- Laboratoire de Physique des Solides, Université Paris Sud & CNRS , 91405 Orsay Cedex, France
| | - Andrew J Haslam
- Department of Chemical Engineering and Qatar Carbonates and Carbon Storage Research Centre, Imperial College London , South Kensington Campus, London SW7 2AZ, United Kingdom
| | - George Jackson
- Department of Chemical Engineering and Qatar Carbonates and Carbon Storage Research Centre, Imperial College London , South Kensington Campus, London SW7 2AZ, United Kingdom
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13
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Binder K, Virnau P. Overview: Understanding nucleation phenomena from simulations of lattice gas models. J Chem Phys 2016; 145:211701. [DOI: 10.1063/1.4959235] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- Kurt Binder
- Institut für Physik, Johannes Gutenberg-Universität, Staudinger Weg 9, D-55099 Mainz, Germany
| | - Peter Virnau
- Institut für Physik, Johannes Gutenberg-Universität, Staudinger Weg 9, D-55099 Mainz, Germany
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14
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Caselle M, Costagliola G, Nada A, Panero M, Toniato A. Jarzynski’s theorem for lattice gauge theory. Int J Clin Exp Med 2016. [DOI: 10.1103/physrevd.94.034503] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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15
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Nagata Y, Ohto T, Bonn M, Kühne TD. Surface tension of ab initio liquid water at the water-air interface. J Chem Phys 2016; 144:204705. [DOI: 10.1063/1.4951710] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023] Open
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16
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Urrutia I, Paganini IE. Virial series for inhomogeneous fluids applied to the Lennard-Jones wall-fluid surface tension at planar and curved walls. J Chem Phys 2016; 144:174102. [DOI: 10.1063/1.4947587] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- Ignacio Urrutia
- Departamento de Física de la Materia Condensada, Centro Atómico Constituyentes, CNEA, Av.Gral. Paz 1499, 1650 Pcia. de Buenos Aires, Argentina and CONICET, Avenida Rivadavia 1917, C1033AAJ Buenos Aires, Argentina
| | - Iván E. Paganini
- Departamento de Física de la Materia Condensada, Centro Atómico Constituyentes, CNEA, Av.Gral. Paz 1499, 1650 Pcia. de Buenos Aires, Argentina and CONICET, Avenida Rivadavia 1917, C1033AAJ Buenos Aires, Argentina
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17
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Nagata Y, Ohto T, Backus EHG, Bonn M. Molecular Modeling of Water Interfaces: From Molecular Spectroscopy to Thermodynamics. J Phys Chem B 2016; 120:3785-96. [DOI: 10.1021/acs.jpcb.6b01012] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Affiliation(s)
- Yuki Nagata
- Max Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz, Germany
| | - Tatsuhiko Ohto
- Graduate
School of Engineering Science, Osaka University, 1-3 Machikaneyama, Toyonaka, Osaka 560-8531, Japan
| | - Ellen H. G. Backus
- Max Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz, Germany
| | - Mischa Bonn
- Max Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz, Germany
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18
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Virnau P, Schmitz F, Binder K. The ensemble switch method and related approaches to obtain interfacial free energies between coexisting phases from simulations: a brief review. MOLECULAR SIMULATION 2015. [DOI: 10.1080/08927022.2015.1071810] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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19
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Schmitz F, Virnau P. The ensemble switch method for computing interfacial tensions. J Chem Phys 2015; 142:144108. [DOI: 10.1063/1.4916317] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
Affiliation(s)
- Fabian Schmitz
- Institute of Physics, Johannes Gutenberg University Mainz, Staudingerweg 9, D-55128 Mainz, Germany
| | - Peter Virnau
- Institute of Physics, Johannes Gutenberg University Mainz, Staudingerweg 9, D-55128 Mainz, Germany
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20
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Benjamin R, Horbach J. Crystal-liquid interfacial free energy of hard spheres via a thermodynamic integration scheme. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2015; 91:032410. [PMID: 25871126 DOI: 10.1103/physreve.91.032410] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/03/2014] [Indexed: 06/04/2023]
Abstract
The hard-sphere crystal-liquid interfacial free energy γcl is determined from molecular dynamics simulations using a thermodynamic integration (TI) scheme. The advantage of this TI scheme compared to previous methods is to successfully circumvent hysteresis effects due to the movement of the crystal-liquid interface. This is accomplished by the use of extremely-short-range and impenetrable Gaussian flat walls that prevent the drift of the interface while imposing a negligible free-energy penalty. We find that it is crucial to analyze finite-size effects in order to obtain reliable estimates of γcl in the thermodynamic limit.
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Affiliation(s)
- Ronald Benjamin
- Institut für Theoretische Physik II: Soft Matter, Heinrich Heine-Universität Düsseldorf, Universitätsstraße 1, 40225 Düsseldorf, Germany
| | - Jürgen Horbach
- Institut für Theoretische Physik II: Soft Matter, Heinrich Heine-Universität Düsseldorf, Universitätsstraße 1, 40225 Düsseldorf, Germany
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21
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Block BJ, Kim S, Virnau P, Binder K. Anisotropic interfacial tension, contact angles, and line tensions: a graphics-processing-unit-based Monte Carlo study of the Ising model. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2014; 90:062106. [PMID: 25615043 DOI: 10.1103/physreve.90.062106] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/21/2014] [Indexed: 06/04/2023]
Abstract
As a generic example for crystals where the crystal-fluid interface tension depends on the orientation of the interface relative to the crystal lattice axes, the nearest-neighbor Ising model on the simple cubic lattice is studied over a wide temperature range, both above and below the roughening transition temperature. Using a thin-film geometry L(x)×L(y)×L(z) with periodic boundary conditions along the z axis and two free L(x)×L(y) surfaces at which opposing surface fields ±H(1) act, under conditions of partial wetting, a single planar interface inclined under a contact angle θ<π/2 relative to the yz plane is stabilized. In the y direction, a generalization of the antiperiodic boundary condition is used that maintains the translational invariance in the y direction despite the inhomogeneity of the magnetization distribution in this system. This geometry allows a simultaneous study of the angle-dependent interface tension, the contact angle, and the line tension (which depends on the contact angle, and on temperature). All these quantities are extracted from suitable thermodynamic integration procedures. In order to keep finite-size effects as well as statistical errors small enough, rather large lattice sizes (of the order of 46 million sites) were found to be necessary, and the availability of very efficient code implementation of graphics processing units was crucial for the feasibility of this study.
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Affiliation(s)
- Benjamin J Block
- Institut für Physik, Johannes Gutenberg-Universität Mainz, Staudinger Weg 9, D-55099 Mainz, Germany
| | - Suam Kim
- Institut für Physik, Johannes Gutenberg-Universität Mainz, Staudinger Weg 9, D-55099 Mainz, Germany
| | - Peter Virnau
- Institut für Physik, Johannes Gutenberg-Universität Mainz, Staudinger Weg 9, D-55099 Mainz, Germany
| | - Kurt Binder
- Institut für Physik, Johannes Gutenberg-Universität Mainz, Staudinger Weg 9, D-55099 Mainz, Germany
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Benjamin R, Horbach J. Crystal-liquid interfacial free energy via thermodynamic integration. J Chem Phys 2014; 141:044715. [DOI: 10.1063/1.4891220] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- Ronald Benjamin
- Institut für Theoretische Physik II: Soft Matter, Heinrich Heine-Universität Düsseldorf, Universitätsstraße 1, 40225 Düsseldorf, Germany
| | - Jürgen Horbach
- Institut für Theoretische Physik II: Soft Matter, Heinrich Heine-Universität Düsseldorf, Universitätsstraße 1, 40225 Düsseldorf, Germany
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Schmitz F, Virnau P, Binder K. Logarithmic finite-size effects on interfacial free energies: phenomenological theory and Monte Carlo studies. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2014; 90:012128. [PMID: 25122272 DOI: 10.1103/physreve.90.012128] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/04/2014] [Indexed: 06/03/2023]
Abstract
The computation of interfacial free energies between coexisting phases (e.g., saturated vapor and liquid) by computer simulation methods is still a challenging problem due to the difficulty of an atomistic identification of an interface and interfacial fluctuations on all length scales. The approach to estimate the interfacial tension from the free-energy excess of a system with interfaces relative to corresponding single-phase systems does not suffer from the first problem but still suffers from the latter. Considering d-dimensional systems with interfacial area L(d-1) and linear dimension L(z) in the direction perpendicular to the interface, it is argued that the interfacial fluctuations cause logarithmic finite-size effects of order ln(L)/L(d-1) and order ln(L(z))/L(d-1), in addition to regular corrections (with leading-order const/L(d-1)). A phenomenological theory predicts that the prefactors of the logarithmic terms are universal (but depend on the applied boundary conditions and the considered statistical ensemble). The physical origin of these corrections are the translational entropy of the interface as a whole, "domain breathing" (coupling of interfacial fluctuations to the bulk order parameter fluctuations of the coexisting domains), and capillary waves. Using a new variant of the ensemble switch method, interfacial tensions are found from Monte Carlo simulations of d = 2 and d = 3 Ising models and a Lennard-Jones fluid. The simulation results are fully consistent with the theoretical predictions.
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Affiliation(s)
- Fabian Schmitz
- Institute of Physics, Johannes Gutenberg University Mainz, Staudingerweg 7, D-55128 Mainz, Germany
| | - Peter Virnau
- Institute of Physics, Johannes Gutenberg University Mainz, Staudingerweg 7, D-55128 Mainz, Germany
| | - Kurt Binder
- Institute of Physics, Johannes Gutenberg University Mainz, Staudingerweg 7, D-55128 Mainz, Germany
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