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Eckert T, Schmidt M, de Las Heras D. Effect of sample height and particle elongation in the sedimentation of colloidal rods. SOFT MATTER 2023; 19:2214-2223. [PMID: 36883340 DOI: 10.1039/d3sm00191a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/18/2023]
Abstract
We study theoretically the effect of a gravitational field on the equilibrium behaviour of a colloidal suspension of rods with different length-to-width aspect ratios. The bulk phases of the system are described with analytical equations of state. The gravitational field is then incorporated via sedimentation path theory, which assumes a local equilibrium condition at each altitude of the sample. The bulk phenomenology is significantly enriched by the presence of the gravitational field. In a suspension of elongated rods with five stable phases in bulk, the gravitational field stabilizes up to fifteen different stacking sequences. The sample height has a non-trivial effect on the stable stacking sequence. New layers of distinct bulk phases appear either at the top, at the bottom, or simultaneously at the top and the bottom when increasing the sample height at constant colloidal concentration. We also study sedimentation in a mass-polydisperse suspension in which all rods have the same shape but different buoyant masses.
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Affiliation(s)
- Tobias Eckert
- Theoretische Physik II, Physikalisches Institut, Universität Bayreuth, D-95440 Bayreuth, Germany.
| | - Matthias Schmidt
- Theoretische Physik II, Physikalisches Institut, Universität Bayreuth, D-95440 Bayreuth, Germany.
| | - Daniel de Las Heras
- Theoretische Physik II, Physikalisches Institut, Universität Bayreuth, D-95440 Bayreuth, Germany.
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2
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Chattopadhyay J, Ramaswamy S, Dasgupta C, Maiti PK. Two-temperature activity induces liquid-crystal phases inaccessible in equilibrium. Phys Rev E 2023; 107:024701. [PMID: 36932588 DOI: 10.1103/physreve.107.024701] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2022] [Accepted: 01/17/2023] [Indexed: 02/08/2023]
Abstract
In equilibrium hard-rod fluids, and in effective hard-rod descriptions of anisotropic soft-particle systems, the transition from the isotropic (I) phase to the nematic phase (N) is observed above the rod aspect ratio L/D=3.70 as predicted by Onsager. We examine the fate of this criterion in a molecular dynamics study of a system of soft repulsive spherocylinders rendered active by coupling half the particles to a heat bath at a higher temperature than that imposed on the other half. We show that the system phase-separates and self-organizes into various liquid-crystalline phases that are not observed in equilibrium for the respective aspect ratios. In particular, we find a nematic phase for L/D=3 and a smectic phase for L/D=2 above a critical activity.
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Affiliation(s)
- Jayeeta Chattopadhyay
- Centre for Condensed Matter Theory, Department of Physics, Indian Institute of Science, Bangalore 560012, India
| | - Sriram Ramaswamy
- Centre for Condensed Matter Theory, Department of Physics, Indian Institute of Science, Bangalore 560012, India
| | - Chandan Dasgupta
- Centre for Condensed Matter Theory, Department of Physics, Indian Institute of Science, Bangalore 560012, India
| | - Prabal K Maiti
- Centre for Condensed Matter Theory, Department of Physics, Indian Institute of Science, Bangalore 560012, India
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3
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Rajendra D, Mandal J, Hatwalne Y, Maiti PK. Packing and emergence of the ordering of rods in a spherical monolayer. SOFT MATTER 2022; 19:137-146. [PMID: 36477473 DOI: 10.1039/d2sm00799a] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/17/2023]
Abstract
Spatially ordered systems confined to surfaces such as spheres exhibit interesting topological structures because of curvature induced frustration in orientational and translational order. The study of these structures is important for investigating the interplay between the geometry, topology, and elasticity, and for their potential applications in materials science, such as engineering directionally binding particles. In this work, we numerically simulate a spherical monolayer of soft repulsive spherocylinders (SRSs) and study the packing of rods and their ordering transition as a function of the packing fraction. In the model that we study, the centers of mass of the spherocylinders (situated at their geometric centers) are constrained to move on a spherical surface. The spherocylinders are free to rotate about any axis that passes through their respective centers of mass. We show that, up to moderate packing fractions, a two dimensional liquid crystalline phase is formed whose orientational ordering increases continuously with increasing density. This monolayer of orientationally ordered SRS particles at medium densities resembles a hedgehog-long axes of the SRS particles are aligned along the local normal to the sphere. At higher packing fractions, the system undergoes a transition to the solid phase, which is riddled with topological point defects (disclinations) and grain boundaries that divide the whole surface into several domains.
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Affiliation(s)
- Dharanish Rajendra
- Centre for Condensed Matter Theory, Department of Physics, Indian Institute of Science, Bengaluru 560012, India.
| | - Jaydeep Mandal
- Centre for Condensed Matter Theory, Department of Physics, Indian Institute of Science, Bengaluru 560012, India.
| | | | - Prabal K Maiti
- Centre for Condensed Matter Theory, Department of Physics, Indian Institute of Science, Bengaluru 560012, India.
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4
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Stengele P, Lüders A, Nielaba P. Group formation and collective motion of colloidal rods with an activity triggered by visual perception. Phys Rev E 2022; 106:014603. [PMID: 35974625 DOI: 10.1103/physreve.106.014603] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2022] [Accepted: 06/23/2022] [Indexed: 06/15/2023]
Abstract
We investigate the formation of cohesive groups and the collective diffusion of colloidal spherocylinders with a motility driven by a simple visual perception model. For this, we perform Brownian dynamics simulations without hydrodynamic interactions. The visual perception is based on sight cones attached to the spherocylinders and perception functions quantifying the visual stimuli. If the perception function of a particle reaches a predefined threshold, an active component is added to its motion. We find that, in addition to the opening angle of the cone of sight, the aspect ratio of the particles plays an important role for the formation of cohesive groups. If the elongation of the particles is increased, the maximum angle for which the rods organize themselves into such groups decreases distinctly. After a system forms a cohesive group, it performs a diffusive motion, which can be quantified by an effective diffusion coefficient. For increasing aspect ratios, the spatial expansion of the cohesive groups and the effective diffusion coefficient of the collective motion increase, while the number of active group members decreases. We also find that a larger particle number, a smaller propulsion velocity of the group members, and a smaller threshold for the visual stimulus increase the maximum opening angle for which cohesive groups form. Based on our results, we expect anisotropic particles to be of great relevance for the adjustability of visual perception-dependent motility.
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Affiliation(s)
- Philipp Stengele
- Statistical and Computational Physics, Department of Physics, University of Konstanz, 78464 Konstanz, Germany
| | - Anton Lüders
- Statistical and Computational Physics, Department of Physics, University of Konstanz, 78464 Konstanz, Germany
| | - Peter Nielaba
- Statistical and Computational Physics, Department of Physics, University of Konstanz, 78464 Konstanz, Germany
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5
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Cywiak D, Gil-Villegas A, Patti A. Long-time relaxation dynamics in nematic and smectic liquid crystals of soft repulsive colloidal rods. Phys Rev E 2022; 105:014703. [PMID: 35193200 DOI: 10.1103/physreve.105.014703] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2021] [Accepted: 01/04/2022] [Indexed: 06/14/2023]
Abstract
Understanding the relaxation dynamics of colloidal suspensions is crucial to identifying the elements that influence the mobility of their constituents, assessing their macroscopic response across the relevant time and length scales, and thus disclosing the fundamentals underpinning their exploitation in formulation engineering. In this work, we specifically assess the impact of long-ranged ordering on the relaxation dynamics of suspensions of soft repulsive rodlike particles, which are able to self-organize into nematic and smectic liquid-crystalline phases. Rods are modeled as soft repulsive spherocylinders with a length-to-diameter ratio L^{★}=5, interacting via the truncated and shifted Kihara potential. By performing dynamic Monte Carlo simulations, we analyze the effect of translational and orientational order on the diffusion of the rods along the relevant directions imposed by the morphology of the background phases. To provide a clear picture of the resulting dynamics, we assess its dependence on temperature, which can dramatically determine the response time of the system relaxation and the self-diffusion coefficients of the rods. The computation of the van Hove correlation functions allows us to identify the existence of rods that diffuse significantly faster than the average and whose concentration can be accurately adjusted by a suitable choice of temperature.
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Affiliation(s)
- Daniela Cywiak
- División de Ciencias e Ingenierías, Universidad de Guanajuato, Campus León, Mexico
| | | | - Alessandro Patti
- Department of Chemical Engineering and Analytical Science, University of Manchester, Manchester M13 9PL, United Kingdom
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6
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Chattopadhyay J, Pannir-Sivajothi S, Varma K, Ramaswamy S, Dasgupta C, Maiti PK. Heating leads to liquid-crystal and crystalline order in a two-temperature active fluid of rods. Phys Rev E 2021; 104:054610. [PMID: 34942740 DOI: 10.1103/physreve.104.054610] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2021] [Accepted: 10/22/2021] [Indexed: 11/07/2022]
Abstract
We report phase separation and liquid-crystal ordering induced by scalar activity in a system of soft repulsive spherocylinders (SRSs) of shape anisotropy L/D=5 using molecular dynamics (MD) simulations. Activity is introduced by increasing the temperature of half of the SRSs (labeled hot) while maintaining the temperature of the other half constant at a lower value (labeled cold). The difference between the two temperatures scaled by the lower temperature provides a measure of the activity. Starting from different equilibrium initial phases, we find that activity leads to segregation of the hot and cold particles. Activity also drives the cold particles through a phase transition to a more ordered state and the hot particles to a state of less order compared to the initial equilibrium state. The cold components of a homogeneous isotropic structure acquire nematic and, at higher activity, crystalline order. Similarly, the cold zone of a nematic initial state undergoes smectic and crystal ordering above a critical value of activity while the hot component turns isotropic. We find that the hot particles occupy a larger volume and exert an extra kinetic pressure, confining, compressing, and provoking an ordering transition of the cold-particle domains.
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Affiliation(s)
- Jayeeta Chattopadhyay
- Centre for Condensed Matter Theory, Department of Physics, Indian Institute of Science, Bangalore 560012, India
| | - Sindhana Pannir-Sivajothi
- Centre for Condensed Matter Theory, Department of Physics, Indian Institute of Science, Bangalore 560012, India
| | - Kaarthik Varma
- Centre for Condensed Matter Theory, Department of Physics, Indian Institute of Science, Bangalore 560012, India
| | - Sriram Ramaswamy
- Centre for Condensed Matter Theory, Department of Physics, Indian Institute of Science, Bangalore 560012, India
| | - Chandan Dasgupta
- Centre for Condensed Matter Theory, Department of Physics, Indian Institute of Science, Bangalore 560012, India
| | - Prabal K Maiti
- Centre for Condensed Matter Theory, Department of Physics, Indian Institute of Science, Bangalore 560012, India
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7
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8
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Kowaguchi A, Brumby PE, Yasuoka K. Phase Transitions and Hysteresis for a Simple Model Liquid Crystal by Replica-Exchange Monte Carlo Simulations. Molecules 2021; 26:1421. [PMID: 33808039 PMCID: PMC7961897 DOI: 10.3390/molecules26051421] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2021] [Revised: 03/01/2021] [Accepted: 03/01/2021] [Indexed: 11/17/2022] Open
Abstract
In this work, the advantages of applying the temperature and pressure replica-exchange method to investigate the phase transitions and the hysteresis for liquid-crystal fluids were demonstrated. In applying this method to the commonly used Hess-Su liquid-crystal model, heat capacity peaks and points of phase co-existence were observed. The absence of a smectic phase at higher densities and a narrow range of the nematic phase were reported. The identity of the crystalline phase of this system was found to a hexagonal close-packed solid. Since the nematic-solid phase transition is strongly first order, care must be taken when using this model not to inadvertently simulate meta-stable nematic states at higher densities. In further analysis, the Weighted Histogram Analysis Method was applied to verify the precise locations of the phase transition points.
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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;
| | - Kenji Yasuoka
- Department of Mechanical Engineering, Keio University, 3-14-1 Hiyoshi, Kohoku-ku, Yokohama 223-8522, Japan;
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9
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Neophytou A, Manoharan VN, Chakrabarti D. Self-Assembly of Patchy Colloidal Rods into Photonic Crystals Robust to Stacking Faults. ACS NANO 2021; 15:2668-2678. [PMID: 33448214 DOI: 10.1021/acsnano.0c07824] [Citation(s) in RCA: 25] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/15/2023]
Abstract
Diamond-structured colloidal photonic crystals are much sought-after for their applications in visible light management because of their ability to support a complete photonic band gap (PBG). However, their realization via self-assembly pathways is a long-standing challenge. This challenge is rooted in three fundamental problems: the design of building blocks that assemble into diamond-like structures, the sensitivity of the PBG to stacking faults, and ensuring that the PBG opens at an experimentally attainable refractive index. Here we address these problems simultaneously using a multipronged computational approach. We use reverse engineering to establish the design principles for the rod-connected diamond structure (RCD), the so-called "champion" photonic crystal. We devise two distinct self-assembly routes for designer triblock patchy colloidal rods, both proceeding via tetrahedral clusters to yield a mixed phase of cubic and hexagonal polymorphs closely related to RCD. We use Monte Carlo simulations to show how these routes avoid a metastable amorphous phase. Finally, we show that both the polymorphs support spectrally overlapping PBGs. Importantly, randomly stacked hybrids of these polymorphs also display PBGs, thus circumventing the requirement of polymorph selection in a scalable fabrication method.
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Affiliation(s)
- Andreas Neophytou
- School of Chemistry, University of Birmingham, Edgbaston, Birmingham B15 2TT, U.K
| | - Vinothan N Manoharan
- Harvard John A. Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, Massachusetts 02138, United States
- Department of Physics, Harvard University, Cambridge, Massachusetts 02138, United States
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10
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Morillo N, Patti A, Cuetos A. Brownian dynamics simulations of oblate and prolate colloidal particles in nematic liquid crystals. J Chem Phys 2019; 150:204905. [DOI: 10.1063/1.5090975] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Affiliation(s)
- Neftalí Morillo
- Department of Physical, Chemical and Natural Systems, Pablo de Olavide University, 41013 Sevilla, Spain
| | - Alessandro Patti
- School of Chemical Engineering and Analytical Science, The University of Manchester, Manchester M13 9PL, United Kingdom
| | - Alejandro Cuetos
- Department of Physical, Chemical and Natural Systems, Pablo de Olavide University, 41013 Sevilla, Spain
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11
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Gámez F, Lago S. The global liquid crystal phase diagram of the nematogenic square-well line model. Mol Phys 2016. [DOI: 10.1080/00268976.2016.1263366] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
Affiliation(s)
- Francisco Gámez
- Department of Physical, Chemical and Natural Systems, Universidad Pablo de Olavide, Seville, Spain
| | - Santiago Lago
- Department of Physical, Chemical and Natural Systems, Universidad Pablo de Olavide, Seville, Spain
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12
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Gámez F. Numerical evaluation of the second virial coefficients of anisotropic multipolar intermolecular potentials. J Mol Liq 2016. [DOI: 10.1016/j.molliq.2016.05.021] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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13
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Chen W, Zhu Y, Cui F, Liu L, Sun Z, Chen J, Li Y. GPU-Accelerated Molecular Dynamics Simulation to Study Liquid Crystal Phase Transition Using Coarse-Grained Gay-Berne Anisotropic Potential. PLoS One 2016; 11:e0151704. [PMID: 26986851 PMCID: PMC4795799 DOI: 10.1371/journal.pone.0151704] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2015] [Accepted: 03/02/2016] [Indexed: 12/26/2022] Open
Abstract
Gay-Berne (GB) potential is regarded as an accurate model in the simulation of anisotropic particles, especially for liquid crystal (LC) mesogens. However, its computational complexity leads to an extremely time-consuming process for large systems. Here, we developed a GPU-accelerated molecular dynamics (MD) simulation with coarse-grained GB potential implemented in GALAMOST package to investigate the LC phase transitions for mesogens in small molecules, main-chain or side-chain polymers. For identical mesogens in three different molecules, on cooling from fully isotropic melts, the small molecules form a single-domain smectic-B phase, while the main-chain LC polymers prefer a single-domain nematic phase as a result of connective restraints in neighboring mesogens. The phase transition of side-chain LC polymers undergoes a two-step process: nucleation of nematic islands and formation of multi-domain nematic texture. The particular behavior originates in the fact that the rotational orientation of the mesogenes is hindered by the polymer backbones. Both the global distribution and the local orientation of mesogens are critical for the phase transition of anisotropic particles. Furthermore, compared with the MD simulation in LAMMPS, our GPU-accelerated code is about 4 times faster than the GPU version of LAMMPS and at least 200 times faster than the CPU version of LAMMPS. This study clearly shows that GPU-accelerated MD simulation with GB potential in GALAMOST can efficiently handle systems with anisotropic particles and interactions, and accurately explore phase differences originated from molecular structures.
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Affiliation(s)
- Wenduo Chen
- Key Laboratory of Synthetic Rubber & Laboratory of Advanced Power Sources, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, 5625 Renmin Street, Changchun, PR China
| | - Youliang Zhu
- State Key Laboratory of Polymer Physics and Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, 5625 Renmin Street, Changchun, PR China
| | - Fengchao Cui
- Key Laboratory of Synthetic Rubber & Laboratory of Advanced Power Sources, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, 5625 Renmin Street, Changchun, PR China
| | - Lunyang Liu
- Key Laboratory of Synthetic Rubber & Laboratory of Advanced Power Sources, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, 5625 Renmin Street, Changchun, PR China
| | - Zhaoyan Sun
- State Key Laboratory of Polymer Physics and Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, 5625 Renmin Street, Changchun, PR China
| | - Jizhong Chen
- State Key Laboratory of Polymer Physics and Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, 5625 Renmin Street, Changchun, PR China
| | - Yunqi Li
- Key Laboratory of Synthetic Rubber & Laboratory of Advanced Power Sources, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, 5625 Renmin Street, Changchun, PR China
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14
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Oyarzún Rivera B, van Westen T, Vlugt TJH. Liquid-crystal phase equilibria of Lennard-Jones chains. Mol Phys 2016. [DOI: 10.1080/00268976.2015.1134824] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
Affiliation(s)
| | - Thijs van Westen
- Process and Energy Laboratory, Delft University of Technology, Delft, The Netherlands
| | - Thijs J. H. Vlugt
- Process and Energy Laboratory, Delft University of Technology, Delft, The Netherlands
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15
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Piedrahita M, Cuetos A, Martínez-Haya B. Transport of spherical colloids in layered phases of binary mixtures with rod-like particles. SOFT MATTER 2015; 11:3432-3440. [PMID: 25797280 DOI: 10.1039/c4sm02865a] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
The transport properties of colloids in anisotropic media constitute a general problem of fundamental interest in experimental sciences, with a broad range of technological applications. This work investigates the transport of soft spherical colloids in binary mixtures with rod-like particles by means of Monte Carlo and Brownian Dynamics simulations. Layered phases are considered, that range from smectic phases to lamellar phases, depending on the molar fraction of the spherical particles. The investigation serves to characterize the distinct features of transport within layers versus those of transport across neighboring layers, both of which are neatly differentiated. The insertion of particles into layers and the diffusion across them occur at a smaller rate than the intralayer diffusion modulated by the formation of transitory cages in its initial stages. Collective events, in which two or more colloids diffuse across layers in a concerted way, are described as a non-negligible process in these fluids.
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Affiliation(s)
- Mauricio Piedrahita
- Department of Physical, Chemical and Natural Systems, Universidad Pablo de Olavide, 41013 Seville, Spain.
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16
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Cuetos A, Martínez-Haya B. Liquid crystal phase diagram of soft repulsive rods and its mapping on the hard repulsive reference fluid. Mol Phys 2015. [DOI: 10.1080/00268976.2014.996191] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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17
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Chapela GA, Díaz-Herrera E, Armas-Pérez JC, Quintana-H J. Effect of flexibility on liquid-vapor coexistence and surface properties of tangent linear vibrating square well chains in two and three dimensions. J Chem Phys 2013; 138:224509. [DOI: 10.1063/1.4807322] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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18
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Jiménez-Serratos G, Vega C, Gil-Villegas A. Evaluation of the pressure tensor and surface tension for molecular fluids with discontinuous potentials using the volume perturbation method. J Chem Phys 2012. [DOI: 10.1063/1.4767375] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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19
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Patti A, Cuetos A. Brownian dynamics and dynamic Monte Carlo simulations of isotropic and liquid crystal phases of anisotropic colloidal particles: a comparative study. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2012; 86:011403. [PMID: 23005413 DOI: 10.1103/physreve.86.011403] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/23/2012] [Revised: 06/14/2012] [Indexed: 06/01/2023]
Abstract
We report on the diffusion of purely repulsive and freely rotating colloidal rods in the isotropic, nematic, and smectic liquid crystal phases to probe the agreement between Brownian and Monte Carlo dynamics under the most general conditions. By properly rescaling the Monte Carlo time step, being related to any elementary move via the corresponding self-diffusion coefficient, with the acceptance rate of simultaneous trial displacements and rotations, we demonstrate the existence of a unique Monte Carlo time scale that allows for a direct comparison between Monte Carlo and Brownian dynamics simulations. To estimate the validity of our theoretical approach, we compare the mean square displacement of rods, their orientational autocorrelation function, and the self-intermediate scattering function, as obtained from Brownian dynamics and Monte Carlo simulations. The agreement between the results of these two approaches, even under the condition of heterogeneous dynamics generally observed in liquid crystalline phases, is excellent.
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Affiliation(s)
- Alessandro Patti
- Institute of Advanced Chemistry of Catalonia, IQAC-CSIC and CIBER de Bioingeniería, Biomateriales y Nanomedicina, Jordi Girona 18-26, 08034 Barcelona, Spain.
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21
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Sarman S, Laaksonen A. The heat conductivity of liquid crystal phases of a soft ellipsoid string-fluid evaluated by molecular dynamics simulation. Phys Chem Chem Phys 2011; 13:5915-25. [PMID: 21336361 DOI: 10.1039/c0cp02617d] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
We have applied a nonequilibrium molecular dynamics heat flow algorithm to calculate the heat conductivity of a molecular model system, which forms uniaxial and biaxial nematic liquid crystals. The model system consists of a soft ellipsoid string-fluid where the ellipsoids interact according to a repulsive version of the Gay-Berne potential. On compression, this system forms discotic or calamitic uniaxial nematic phases depending on the dimensions of the molecules, and on further compression a biaxial nematic phase is formed. In the discotic nematic phase, the heat conductivity has two components, one parallel and one perpendicular to the director, where the last mentioned component is the largest one. This order of magnitudes is reversed in the calamitic nematic phase. In the biaxial nematic phase there are three components of the heat conductivity, one in the direction around which the long axes of the molecules are oriented, this is the largest component, another one in the direction around which the normals of the broadsides of the molecules are oriented, this is the smallest component, and one in the direction perpendicular to these two directions with a magnitude in between those of the first mentioned components. The relative magnitudes of the components of the heat conductivity span a fairly wide interval so it should be possible to use the model to parameterise experimental data.
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Affiliation(s)
- Sten Sarman
- Department of Materials and Environmental Chemistry, Stockholm University, Stockholm, Sweden.
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22
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Cao QL, Wang WL, Li YD, Liu CS. Correlations among residual multiparticle entropy, local atomic-level pressure, free volume and the phase-ordering rule in several liquids. J Chem Phys 2011; 134:044508. [DOI: 10.1063/1.3524206] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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23
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Triplett DA, Quimby LM, Smith BD, Rodríguez DH, St. Angelo SK, González P, Keating CD, Fichthorn KA. Assembly of gold nanowires by sedimentation from suspension: Experiments and simulation. THE JOURNAL OF PHYSICAL CHEMISTRY. C, NANOMATERIALS AND INTERFACES 2010; 114:7346-7355. [PMID: 20544001 PMCID: PMC2882699 DOI: 10.1021/jp909251v] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
We investigated the ordering of gold nanowires that settled from aqueous suspension onto a glass substrate due to gravity. The nanowires, ca. 300 nm in cross-sectional diameter and ca. 2, 4, or 7 microns in length, were coated with 2-mercaptoethanesulfonic acid to provide electrostatic repulsion and prevent aggregation. The layer of nanowires in direct contact with the substrate was examined from below using optical microscopy and found to exhibit smectic-like ordering. The extent of smectic ordering depended on nanowire length with the shortest (2 μm) nanowires exhibiting the best ordering. To understand the assembly in this system, we used canonical Monte Carlo simulations to model the two-dimensional ordering of the nanowires on a substrate. We accounted for van der Waals and electrostatic interactions between the nanowires. The simulations reproduced the experimental trends and showed that roughness at the ends of the nanowires, which locally increased electrostatic repulsion, is critical to correctly predicting the experimentally observed smectic ordering.
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Martínez-Haya B, Cuetos A. Simulation study of discotic molecules in the vicinity of the isotropic–liquid crystal transition. MOLECULAR SIMULATION 2009. [DOI: 10.1080/08927020902833111] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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25
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Green MJ, Parra-Vasquez ANG, Behabtu N, Pasquali M. Modeling the phase behavior of polydisperse rigid rods with attractive interactions with applications to single-walled carbon nanotubes in superacids. J Chem Phys 2009; 131:084901. [DOI: 10.1063/1.3204024] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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26
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Martínez-Haya B, Cuetos A. Columnar phases of discotics with orientation-dependent interactions. J Chem Phys 2009; 131:074901. [DOI: 10.1063/1.3207284] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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27
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Lintuvuori JS, Wilson MR. A coarse-grained simulation study of mesophase formation in a series of rod–coil multiblock copolymers. Phys Chem Chem Phys 2009; 11:2116-25. [DOI: 10.1039/b818616b] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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28
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Cuetos A, Martínez-Haya B. Columnar phases of discotic spherocylinders. J Chem Phys 2008; 129:214706. [DOI: 10.1063/1.3028539] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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29
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Slim HA, Wilson MR. Toward Large Scale Parallelization for Molecular Dynamics of Small Chemical Systems: A Combined Parallel Tempering and Domain Decomposition Approach. J Chem Theory Comput 2008; 4:1570-5. [DOI: 10.1021/ct800255r] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Affiliation(s)
- Henk A. Slim
- Department of Chemistry, University of Durham, South Road, Durham, DH1 3LE, U.K
| | - Mark R. Wilson
- Department of Chemistry, University of Durham, South Road, Durham, DH1 3LE, U.K
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30
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Gámez F, Lago S, Garzón B, Merkling PJ, Vega C. Vapour–liquid equilibrium of fluids composed by oblate molecules. Mol Phys 2008. [DOI: 10.1080/00268970802129826] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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31
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Martínez-Haya B, Cuetos A. Stability of Nematic and Smectic Phases in Rod-Like Mesogens with Orientation−Dependent Attractive Interactions. J Phys Chem B 2007; 111:8150-7. [PMID: 17592869 DOI: 10.1021/jp0715171] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The stability of isotropic (I), nematic (N), smectic A (Sm A), and hexatic (Hex) liquid crystalline phases is studied for a fluid of molecules with a rod-like shape and dispersive interactions dependent on orientation. The fluid is modeled with the spherocylindrical Gay-Berne-Kihara interaction potential proposed in a recent work, with parameters favoring parallel pair orientations. The liquid crystal phase diagram is characterized for different molecular aspect ratios by means of Monte Carlo simulations in the isobaric-isothermal ensemble. Three types of triple points are observed, namely, I-Sm A-Hex, I-N-Sm A, and N-Sm A-Hex, leading to island-shape domains for the smectic A phase. The resulting phase diagrams are compared with those derived previously for prolate fluids of ellipsoidal and spherocylindrical symmetry. It is concluded that the stability of the layered phases with respect to the nematic phase is enhanced in the spherocylindrical fluids due to geometrical constraints. Furthermore, the anisotropy of the dispersive interactions induces a stronger dependence of the overall phase diagram on temperature and aids in the energetic stabilization of the hexatic crystalline phase with respect to the fluid smectic A phase.
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Affiliation(s)
- B Martínez-Haya
- Departamento de Sistemas Físicos, Químicos y Naturales, Universidad Pablo de Olavide, 41013 Seville, Spain
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32
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Peláez J, Wilson M. Molecular orientational and dipolar correlation in the liquid crystal mixture E7: a molecular dynamics simulation study at a fully atomistic level. Phys Chem Chem Phys 2007; 9:2968-75. [PMID: 17551620 DOI: 10.1039/b614422e] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Molecular dynamics simulations are reported for the four component nematic liquid crystal mixture E7, which is used commercially. We are able to show the growth of a nematic phase directly from an isotropic liquid over a 100 ns period for an all-atom model, and study orientational and dipole order within the nematic phase. The simulations show that the cyanoterphenyl component of the mixture, 5CT, is more ordered than the three cyanobiphenyl components. The simulations show also that both parallel and anti-parallel dipole correlation take place in E7 but that the strong anti-parallel dipole correlation is localised to particular arrangements of molecules. It is possible to identify two key preferred configurations for molecular pairs in the fluid, which explain the form of the dipole correlation function, g(1)(r).
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Affiliation(s)
- Jorge Peláez
- Department of Chemistry, Durham University, South Road, Durham, UKDH1 3LE.
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33
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Cao D, Zhu M, Wang W. Microstructure and Self-Assembly of Inhomogeneous Rigid Rodlike Chains between Two Neutral Surfaces: A Hybrid Density Functional Approach. J Phys Chem B 2006; 110:21882-9. [PMID: 17064154 DOI: 10.1021/jp064040m] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
We use a hybrid density functional approach to investigate the microstructure and self-assembly of inhomogeneous rigid rodlike chains between two neutral surfaces, i.e., two hard walls. In the calculation, the rodlike molecule is modeled as a rigid rod linearly connected by the tangent sphere beads. The hybrid method combines a single-chain Monte Carlo (MC) simulation for the ideal-gas part of Helmholtz energy and a DFT approach for the excess Helmholtz energy. The DFT approach includes a modified fundamental measure theory for the excluded-volume effect, the first order thermodynamics perturbation theory for chain connectivity, and the mean field approximation for the van der Waals attraction. We investigate the effect of the chain length (i.e., aspect ratio) of the rodlike molecule and the separation between two surfaces on the microstructure and self-assembly of inhomogeneous rigid rodlike chains. For the athermal systems, the rodlike chain fluids present a smaller partitioning coefficient compared to the flexible chain fluids. For the thermal systems, lamellar thin films formed by the rigid rodlike molecules perpendicular to the neutral surface are observed. The effects of the head-head interaction and the separation on the self-assembly of the rodlike chain fluids in the slit are investigated.
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Affiliation(s)
- Dapeng Cao
- Lab of Molecular and Materials Simulation, College of Chemical Engineering, Beijing University of Chemical Technology, Beijing 100029, P R China.
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34
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Abstract
A molecular level model for lipid bilayers is presented. Lipids are represented by rigid, asymmetric, soft spherocylinders in implicit solvent. A simple three parameter potential between pairs of lipids gives rise to a rich assortment of phases including (but not limited to) micelles, fluid bilayers, and gel-like bilayers. Monte Carlo simulations have been carried out to verify self-assembly, characterize the phases corresponding to different potential parametrizations, and to quantify the physical properties associated with those parameter sets corresponding to fluid bilayer behavior. The studied fluid bilayers have compressibility moduli in agreement with experimental systems, but display bending moduli at least three times larger than typical biological membranes without cholesterol.
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Affiliation(s)
- Grace Brannigan
- Department of Physics and Astronomy, University of California, Santa Barbara, California 93106, USA
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35
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Hughes ZE, Wilson MR, Stimson LM. Coarse-grained simulation studies of a liquid crystal dendrimer: towards computational predictions of nanoscale structure through microphase separation. SOFT MATTER 2005; 1:436-443. [PMID: 32646112 DOI: 10.1039/b511082c] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Coarse-grained simulations are described in which the behaviour of a system of model liquid crystalline dendrimer molecules is studied in both liquid and smectic-A liquid crystalline phases. The model system is based on a third generation carbosilane dendrimer, which is functionalised at the surface by short polymeric chains terminated in mesogenic units. The design of the coarse-grained model is based on initial Monte Carlo studies of a single carbosilane molecule at an atomistic level, which yield structural data. The coarse-grained dendrimer is represented in terms of a combination of spherical sites representing the dendrimer core and polymer chains, and spherocylinders representing the mesogenic groups. A strong coupling is seen between internal molecular structure and molecular environment, with individual dendrimer molecules undergoing a remarkable transition from spherical to rod-shaped at the isotropic-smectic phase transition. The driving force for mesophase formation is provided by nanoscale microphase separation of mesogens and the dendrimer core.
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Affiliation(s)
- Zak E Hughes
- Department of Chemistry, University of Durham, South Road, Durham, DH1 3LE, UK.
| | - Mark R Wilson
- Department of Chemistry, University of Durham, South Road, Durham, DH1 3LE, UK.
| | - Lorna M Stimson
- Biophysics and Statistical Mechanics Group, Laboratory of Computational Engineering, Helsinki University of Technology, P.O. Box 9203, 02015-HUT, Finland.
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36
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Cortada M, Calero S, Lago S. A new insight on the structural changes of linear quadrupole liquids. J Chem Phys 2005; 123:184502. [PMID: 16292909 DOI: 10.1063/1.2102808] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
Molecular-dynamics simulations for linear quadrupole liquids are presented. The study is carried out for two different molecular lengths at constant density and a number of temperatures and quadrupole moments. All the simulated thermodynamic states correspond to the condensed phases and some of them show typical features of a solid structure. Furthermore, a change on the preferred intermolecular orientation in the liquid phase is observed from a shifted parallel molecular arrangement to a perpendicular orientation as the quadrupole raises. This change depends on the quadrupole moment as well as on the molecular length and is put in relation with the solid structure of different "diatomic" molecules such as nitrogen, ethane, and acetylene. The appearance of a plastic solid phase at low quadrupole moment and density is also justified. A thoroughly discussion about the availability of classical perturbation theories for this kind of systems is presented.
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Affiliation(s)
- María Cortada
- Departamento Ciencias Ambientales, University Pablo de Olavide, Carretera de Utrera Km. 1, Seville 41013, Spain
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37
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Cuetos A, Martínez-Haya B, Lago S, Rull LF. Parsons−Lee and Monte Carlo Study of Soft Repulsive Nematogens. J Phys Chem B 2005; 109:13729-36. [PMID: 16852720 DOI: 10.1021/jp051834c] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
A general approach based on the Parsons-Lee theory for soft repulsive molecular fluids is employed to investigate the nematogenic behavior of prolate thermotropic liquid crystals over a broad temperature range. The theory is solved for the particular case of the Kihara soft repulsive spherocylinder model, which is mapped into an effective hard core interaction with a temperature-dependent molecular diameter, expected to resemble the average size and shape of the soft molecules at a given temperature. The reduction of the effective molecular diameter with temperature in the Kihara soft repulsive fluid implies implicitly an increase of the elongation of the molecule and induces the stabilization of the nematic phase at smaller effective packing fractions, contrary to what is found for other fluid models. The rationalization of this effect in terms of excluded volume steric arguments is corroborated by the good general agreement between the Parsons-Lee approach and Monte Carlo simulations for the equation of state of the fluid in the vicinity of the isotropic-nematic transition.
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Affiliation(s)
- A Cuetos
- Departamento de Ciencias Ambientales, Universidad Pablo de Olavide, 41013 Seville, Spain
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38
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Li W, Ma HR. Depletion interactions between two spherocylinders. THE EUROPEAN PHYSICAL JOURNAL. E, SOFT MATTER 2005; 16:225-231. [PMID: 15729514 DOI: 10.1140/epje/e2005-00024-y] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/17/2004] [Indexed: 05/24/2023]
Abstract
The depletion interactions between two spherocylinders as functions of their separation and their relative orientation, induced by a small hard-sphere fluid, are calculated by Monte Carlo simulations using the acceptance ratio method (ARM). The torque on the spherocylinders is determined from the resulting potential. The calculation shows that the ARM is an effective way to obtain depletion interactions of spherocylinders. The depletion interaction under the Asakura-Oosawa (also excluded-volume) approximation is also calculated numerically.
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Affiliation(s)
- W Li
- Institute of Theoretical Physics, Shanghai Jiao Tong University, Shanghai 200240, China.
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39
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Brannigan G, Tamboli AC, Brown FLH. The role of molecular shape in bilayer elasticity and phase behavior. J Chem Phys 2004; 121:3259-71. [PMID: 15291638 DOI: 10.1063/1.1770569] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
A previously developed molecular level model for lipid bilayers [G. Brannigan and F. L. H. Brown, J. Chem. Phys. 120, 1059 (2004)] is extended to allow for variations in lipid length and simulations under constant surface tension conditions. The dependence of membrane elasticity on bilayer thickness is obtained by adjusting lipid length at constant temperature and surface tension. Additionally, bilayer fluidity at various lipid lengths is quantified by analysis of a length versus temperature phase diagram at vanishing tension. Regions of solid, gel-like (hexatic) and fluid bilayer behavior are established by identification of phase boundaries. The main melting transition is found to be density driven; the melting temperature scales inversely with lipid length since thermal expansion increases with lipid aspect ratio.
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Affiliation(s)
- Grace Brannigan
- Department of Physics and Astronomy, University of California, Santa Barbara 93106, USA
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40
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Saija F, Saitta AM, Giaquinta PV. Statistical entropy and density maximum anomaly in liquid water. J Chem Phys 2003. [DOI: 10.1063/1.1598431] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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41
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Costa D, Saija F, Giaquinta PV. Smectic Ordering of Parallel Hard Spherocylinders: An Entropy-Based Monte Carlo Study. J Phys Chem B 2003. [DOI: 10.1021/jp0345001] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- D. Costa
- Dipartimento di Fisica, Istituto Nazionale per la Fisica della Materia (INFM) and Università degli Studi di Messina, Contrada Papardo, C.P. 50-98166 Messina, Italy, and Istituto per i Processi Chimico-Fisici, CNR, sez. Messina, Via La Farina, 237-98123 Messina, Italy
| | - F. Saija
- Dipartimento di Fisica, Istituto Nazionale per la Fisica della Materia (INFM) and Università degli Studi di Messina, Contrada Papardo, C.P. 50-98166 Messina, Italy, and Istituto per i Processi Chimico-Fisici, CNR, sez. Messina, Via La Farina, 237-98123 Messina, Italy
| | - P. V. Giaquinta
- Dipartimento di Fisica, Istituto Nazionale per la Fisica della Materia (INFM) and Università degli Studi di Messina, Contrada Papardo, C.P. 50-98166 Messina, Italy, and Istituto per i Processi Chimico-Fisici, CNR, sez. Messina, Via La Farina, 237-98123 Messina, Italy
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42
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Cuetos A, Martínez-Haya B, Lago S, Rull LF. Liquid crystal behavior of the Kihara fluid. PHYSICAL REVIEW E 2003; 68:011704. [PMID: 12935159 DOI: 10.1103/physreve.68.011704] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/28/2003] [Indexed: 11/07/2022]
Abstract
The liquid crystal phases of the Kihara fluid have been studied in computer simulations. The work focuses on the isotropic-nematic-smectic-A triple point region, especially relevant for the understanding of the properties and the design of real mesogens with specific phase diagrams. The Kihara interaction resembles more appropriately than other related models, the shape of elongated polymers and biomolecules, and a closer assertion is provided for the role of the configurational entropy and the dispersive interactions in the behavior of such molecules in dense phases or under macromolecular crowding conditions.
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Affiliation(s)
- A Cuetos
- Departamento de Ciencias Ambientales, Universidad Pablo de Olavide, 41013 Seville, Spain
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43
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Martínez-Haya B, Cuetos A, Lago S. Solution of the Percus-Yevick equation for square well spherocylinders. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2003; 67:051201. [PMID: 12786138 DOI: 10.1103/physreve.67.051201] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/22/2002] [Revised: 01/13/2003] [Indexed: 05/24/2023]
Abstract
The Percus-Yevick equation for square-well spherocylinders has been numerically solved for some selected orientations following a methodology proposed previously for different fluids of elongated molecules. The equation is solved for particles of aspect ratios ranging from L/sigma=0.3 up to L/sigma=5.0, attractive range lambda/sigma=1.5, and packing fractions within eta=0.1-0.3. The resulting pair correlation functions are checked against isothermal-isobaric Monte Carlo simulations and good agreement is found for the short-range structure, at intermolecular distances within one molecular diameter sigma to contact for each of the selected orientations. At larger distances, the integral equation tends to overestimate the pair correlations. The results confirm the prediction of reference-system average Mayer-function perturbation theory for short aspect ratios, reaching the Onsager limit for the greater aspect ratios. Some instabilities of the solution for the longest models and higher densities are tentatively discussed in terms of their possible relation to frustration phenomena found in some polymer and complex systems.
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Affiliation(s)
- B Martínez-Haya
- Departamento de Ciencias Ambientales, Facultad de Ciencias Experimentales, Universidad Pablo de Olavide, Ctra. de Utrera Km 1, 41013 Seville, Spain.
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44
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Costa D, Micali F, Saija F, Giaquinta PV. Entropy and Correlations in a Fluid of Hard Spherocylinders: The Onset of Nematic and Smectic Order. J Phys Chem B 2002. [DOI: 10.1021/jp0259317] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- D. Costa
- Istituto Nazionale per la Fisica della Materia (INFM) and Università degli Studi di Messina, Dipartimento di Fisica, Contrada Papardo, C.P. 50-98166 Messina, Italy, and CNRIstituto per i Processi Chimico-Fisici, sez. Messina, Via La Farina 237-98123 Messina, Italy
| | - F. Micali
- Istituto Nazionale per la Fisica della Materia (INFM) and Università degli Studi di Messina, Dipartimento di Fisica, Contrada Papardo, C.P. 50-98166 Messina, Italy, and CNRIstituto per i Processi Chimico-Fisici, sez. Messina, Via La Farina 237-98123 Messina, Italy
| | - F. Saija
- Istituto Nazionale per la Fisica della Materia (INFM) and Università degli Studi di Messina, Dipartimento di Fisica, Contrada Papardo, C.P. 50-98166 Messina, Italy, and CNRIstituto per i Processi Chimico-Fisici, sez. Messina, Via La Farina 237-98123 Messina, Italy
| | - P. V. Giaquinta
- Istituto Nazionale per la Fisica della Materia (INFM) and Università degli Studi di Messina, Dipartimento di Fisica, Contrada Papardo, C.P. 50-98166 Messina, Italy, and CNRIstituto per i Processi Chimico-Fisici, sez. Messina, Via La Farina 237-98123 Messina, Italy
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