The Experts below are selected from a list of 5538 Experts worldwide ranked by ideXlab platform
Ilja J Siepmann - One of the best experts on this subject based on the ideXlab platform.
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effects of electrolytes on thermodynamics and structure of oligo ethylene oxide salt solutions and liquid liquid equilibria of a squalane tetraethylene glycol dimethyl ether blend
Macromolecules, 2021Co-Authors: Zhengyuan Shen, Qile P Chen, Shuyi Xie, Timothy P Lodge, Ilja J SiepmannAbstract:Gibbs Ensemble Monte Carlo simulations for salt-doped oligo(ethylene oxide) (OEO, Mw = 90–266 g/mol) solutions show that the presence of ions leads to significant increases in the cohesive energy d...
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probing additive loading in the lamellar phase of a nonionic surfactant Gibbs Ensemble monte carlo simulations using the sdk force field
Langmuir, 2018Co-Authors: Mona S Minkara, Rebecca K Lindsey, Robert H Hembree, Connor L Venteicher, Sumanth N Jamadagni, David M Eike, Ahmad F Ghobadi, Peter H Koenig, Ilja J SiepmannAbstract:Understanding solute uptake into soft microstructured materials, such as bilayers and worm-like and spherical micelles, is of interest in the pharmaceutical, agricultural, and personal care industries. To obtain molecular-level insight on the effects of solutes loading into a lamellar phase, we utilize the Shinoda–Devane–Klein (SDK) coarse-grained force field in conjunction with configurational-bias Monte Carlo simulations in the osmotic Gibbs Ensemble. The lamellar phase is comprised of a bilayer formed by triethylene glycol mono-n-decyl ether (C10E3) surfactants surrounded by water with a 50:50 surfactant/water weight ratio. We study both the unary adsorption isotherm and the effects on bilayer structure and stability caused by n-nonane, 1-hexanol, and ethyl butyrate at several different reduced reservoir pressures. The nonpolar n-nonane molecules load near the center of the bilayer. In contrast, the polar 1-hexanol and ethyl butyrate molecules both load with their polar bead close to the surfactant hea...
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Probing Additive Loading in the Lamellar Phase of a Nonionic Surfactant: Gibbs Ensemble Monte Carlo Simulations Using the SDK Force Field
2018Co-Authors: Mona S Minkara, Rebecca K Lindsey, Robert H Hembree, Connor L Venteicher, Sumanth N Jamadagni, David M Eike, Ahmad F Ghobadi, Peter H Koenig, Ilja J SiepmannAbstract:Understanding solute uptake into soft microstructured materials, such as bilayers and worm-like and spherical micelles, is of interest in the pharmaceutical, agricultural, and personal care industries. To obtain molecular-level insight on the effects of solutes loading into a lamellar phase, we utilize the Shinoda–Devane–Klein (SDK) coarse-grained force field in conjunction with configurational-bias Monte Carlo simulations in the osmotic Gibbs Ensemble. The lamellar phase is comprised of a bilayer formed by triethylene glycol mono-n-decyl ether (C10E3) surfactants surrounded by water with a 50:50 surfactant/water weight ratio. We study both the unary adsorption isotherm and the effects on bilayer structure and stability caused by n-nonane, 1-hexanol, and ethyl butyrate at several different reduced reservoir pressures. The nonpolar n-nonane molecules load near the center of the bilayer. In contrast, the polar 1-hexanol and ethyl butyrate molecules both load with their polar bead close to the surfactant head groups. Near the center of the bilayer, none of the solute molecules exhibits a significant orientational preference. Solute molecules adsorbed near the polar groups of the surfactant chains show a preference for orientations perpendicular to the interface, and this alignment with the long axis of the surfactant molecules is most pronounced for 1-hexanol. Loading of n-nonane leads to an increase of the bilayer thickness, but does not affect the surface area per surfactant. Loading of polar additives leads to both lateral and transverse swelling. The reduced Henry’s law constants of adsorption (expressed as a molar ratio of additive to surfactant per reduced pressure) are 0.23, 1.4, and 14 for n-nonane, 1-hexanol, and ethyl butyrate, respectively, and it appears that the SDK force field significantly overestimates the ethyl butyrate–surfactant interactions
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direct calculation of henry s law constants from Gibbs Ensemble monte carlo simulations nitrogen oxygen carbon dioxide and methane in ethanol
Theoretical Chemistry Accounts, 2006Co-Authors: Ling Zhang, Ilja J SiepmannAbstract:Configurational-bias Monte Carlo simulations in the Gibbs Ensemble were used to calculate Henry’s law constants, Ostwald solubilities, and Gibbs free energies of transfer for oxygen, nitrogen, methane, and carbon dioxide in ethanol at 323 and 373 K. These three solubility descriptors can be expressed as functions of mechanical properties that are directly observable in the Gibbs Ensemble approach, thereby allowing for very precise determination of the descriptors. Additionally, the Henry’s law constants of multiple solutes can be computed from a single simulation. Most of the simulations were carried out for systems containing 1,000 solvent and up to 8 solute molecules, and further simulations using either 500 or 2,000 solvent molecules point to negligible system size effects. A comparison with experimental data shows that the united-atom version of the transferable potential for phase equilibria force field yields Henry’s law constants that reproduce well the differences between the four solutes and the changes upon increase of the temperature.
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vapor liquid equilibria of mixtures containing alkanes carbon dioxide and nitrogen
Aiche Journal, 2001Co-Authors: Jeffrey J Potoff, Ilja J SiepmannAbstract:New force fields for carbon dioxide and nitrogen are introduced that quantitatively reproduce the vapor–liquid equilibria (VLE) of the neat systems and their mixtures with alkanes. In addition to the usual VLE calculations for pure CO2 and N2, calculations of the binary mixtures with propane were used in the force-field development to achieve a good balance between dispersive and electrostatic (quadrupole–quadrupole) interactions. The transferability of the force fields was then assessed from calculations of the VLE for the binary mixtures with n-hexane, the binary mixture of CO2/N2, and the ternary mixture of CO2 /N2/propane. The VLE calculations were carried out using configurational-bias Monte Carlo simulations in either the grand canonical Ensemble with histogram–reweighting or in the Gibbs Ensemble.
Kirill Pavlenko - One of the best experts on this subject based on the ideXlab platform.
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generalized eigenstate thermalization hypothesis in 2d conformal field theories
Physical Review Letters, 2019Co-Authors: Anatoly Dymarsky, Kirill PavlenkoAbstract:Infinite-dimensional conformal symmetry in two dimensions leads to integrability of 2D conformal field theories (CFTs) by giving rise to an infinite tower of local conserved quantum Korteweg--de Vries (qKdV) charges in involution. We discuss how the presence of conserved charges constrains equilibration in 2D CFTs. We propose that in the thermodynamic limit large central charge 2D CFTs satisfy generalized eigenstate thermalization, with the values of qKdV charges forming a complete set of thermodynamically relevant quantities, which unambiguously determine expectation values of all local observables from the vacuum family. Equivalence of Ensembles further provides that local properties of an eigenstate can be described by the generalized Gibbs Ensemble that includes only qKdV charges. In the case of a general initial state, upon equilibration, the emerging generalized Gibbs Ensemble will necessarily include negative chemical potentials and holographically will be described by a quasiclassical black hole with quantum soft hair.
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generalized Gibbs Ensemble of 2d cfts at large central charge in the thermodynamic limit
Journal of High Energy Physics, 2019Co-Authors: Anatoly Dymarsky, Kirill PavlenkoAbstract:We discuss partition function of 2d CFTs decorated by higher qKdV charges in the thermodynamic limit when the size of the spatial circle goes to infinity. In this limit the saddle point approximation is exact and at infinite central charge generalized partition function can be calculated explicitly. We show that leading 1/c corrections to free energy can be reformulated as a sum over Young tableaux which we calculate for the first two qKdV charges. Next, we compare generalized Ensemble with the “eigenstate Ensemble” that consists of a single primary state. At infinite central charge the Ensembles match at the level of expectation values of local operators for any values of qKdV fugacities. When the central charge is large but finite, for any values of the fugacities the aforementioned Ensembles are distinguishable.
Ilja J Siepma - One of the best experts on this subject based on the ideXlab platform.
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prediction of the bubble point pressure for the binary mixture of ethanol and 1 1 1 2 3 3 3 heptafluoropropane from Gibbs Ensemble monte carlo simulations using the trappe force field
Fluid Phase Equilibria, 2007Co-Authors: Neeraj Rai, Jake L Rafferty, Amitesh Maiti, Ilja J SiepmaAbstract:Abstract Configurational-bias Monte Carlo simulations in the Gibbs Ensemble using the TraPPE force field were carried out to predict the pressure–composition diagrams for the binary mixture of ethanol and 1,1,1,2,3,3,3-heptafluoropropane at 283.17 and 343.13 K. A new approach is introduced that allows one to scale predictions at one temperature based on the differences in Gibbs free energies of transfer between experiment and simulation obtained at another temperature. A detailed analysis of the molecular structure and hydrogen bonding for this fluid mixture is provided.
Richard J Sadus - One of the best experts on this subject based on the ideXlab platform.
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molecular simulation of fluids theory algorithms and object orientation
1999Co-Authors: Richard J SadusAbstract:Preface. List of Algorithms. Notation. 1. Introduction. What is molecular simulation? Progress in molecular simulation. 2. Theoretical Foundations. Basic statistical mechanics. Particle dynamics. Summary. 3. Intermolecular Potentials. Calculation of the potential energy. Intermolecular forces. Pairwise potentials for atoms and simple molecules. Contributions to molecular interactions. Simple pairwise potentials for molecules. Pairwise potentials from molecular mechanics. Many-body interactions for atoms. Many-body interactions for molecules. Ab initio calculations. Summary. 4. Calculating Molecular Interactions. Calculation of short-range interactions. Calculation of long-range interactions. Summary. 5. Monte Carlo Simulation. Basic concepts. Application to molecules. Some recent developments. Summary. 6. Integrators for Molecular Dynamics. Integrating the equations of motion. Gear predictor-corrector methods. Verlet predictor methods. Comparison of integrators. Integrators for molecules. Summary. 7. Non-Equilibrium Molecular Dynamics. Synthetic NEMD algorithms. Application of NEMD algorithms to molecules. Application of NEMD algorithms to mixtures. Comparison with equilibrium molecular dynamics. Summary. 8. Molecular Simulation of Ensembles. Monte Carlo methods. Molecular dynamics. Summary. 9. Molecular Simulation of Phase Equilibria. Calculating the chemical potential. Monte Carlo grand canonical Gibbs Ensemble. Molecular dynamics grand canonical Gibbs Ensemble. NPT + test particle. Gibbs-Duhem integration. Thermodynamic scaling. Pseudo Ensemble methods. Histogram re-weighting algorithms. Finite size scaling. Summary. 10. Molecular Simulation and Object-Orientation. Fundamental concepts of object-orientation. Application of object-orientation to microcanonical molecular dynamics simulation of Lennard-Jones atoms. Application of object-orientation to a microcanonical Monte Carlo simulation of Lennard-Jones atoms. Combined molecular dynamics and Monte Carlo program for Lennard-Jones atoms in the microcanonical Ensemble. Extensions. Summary. Appendices: A. Software User's Guide. B. Simulation Resources. Index.
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molecular simulation of fluids theory algorithms and object orientation
1999Co-Authors: Richard J SadusAbstract:Preface. List of Algorithms. Notation. 1. Introduction. What is molecular simulation? Progress in molecular simulation. 2. Theoretical Foundations. Basic statistical mechanics. Particle dynamics. Summary. 3. Intermolecular Potentials. Calculation of the potential energy. Intermolecular forces. Pairwise potentials for atoms and simple molecules. Contributions to molecular interactions. Simple pairwise potentials for molecules. Pairwise potentials from molecular mechanics. Many-body interactions for atoms. Many-body interactions for molecules. Ab initio calculations. Summary. 4. Calculating Molecular Interactions. Calculation of short-range interactions. Calculation of long-range interactions. Summary. 5. Monte Carlo Simulation. Basic concepts. Application to molecules. Some recent developments. Summary. 6. Integrators for Molecular Dynamics. Integrating the equations of motion. Gear predictor-corrector methods. Verlet predictor methods. Comparison of integrators. Integrators for molecules. Summary. 7. Non-Equilibrium Molecular Dynamics. Synthetic NEMD algorithms. Application of NEMD algorithms to molecules. Application of NEMD algorithms to mixtures. Comparison with equilibrium molecular dynamics. Summary. 8. Molecular Simulation of Ensembles. Monte Carlo methods. Molecular dynamics. Summary. 9. Molecular Simulation of Phase Equilibria. Calculating the chemical potential. Monte Carlo grand canonical Gibbs Ensemble. Molecular dynamics grand canonical Gibbs Ensemble. NPT + test particle. Gibbs-Duhem integration. Thermodynamic scaling. Pseudo Ensemble methods. Histogram re-weighting algorithms. Finite size scaling. Summary. 10. Molecular Simulation and Object-Orientation. Fundamental concepts of object-orientation. Application of object-orientation to microcanonical molecular dynamics simulation of Lennard-Jones atoms. Application of object-orientation to a microcanonical Monte Carlo simulation of Lennard-Jones atoms. Combined molecular dynamics and Monte Carlo program for Lennard-Jones atoms in the microcanonical Ensemble. Extensions. Summary. Appendices: A. Software User's Guide. B. Simulation Resources. Index.
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molecular simulation of henry s constant at vapor liquid and liquid liquid phase boundaries
Journal of Physical Chemistry B, 1997Co-Authors: Richard J SadusAbstract:The Gibbs Ensemble is implemented to determine Henry's constant from the residual chemical potential at infinite dilution at the vapor−liquid and liquid−liquid phase boundaries. Results are reported for 12 different single solvent + solute systems at several temperatures between the triple point and critical point of the solvent. The effect of solvent polarity and different solvent−solute dispersion interactions are investigated. Solvent−solute and solvent−solvent interactions are represented by either Lennard-Jones or Keesom intermolecular potentials. The temperature at which the residual chemical potential at infinite dilution equals zero is estimated. Simulations are also reported for three different mixed solvent + solute systems at conditions for liquid−liquid coexistence.
Herbert Spohn - One of the best experts on this subject based on the ideXlab platform.
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Collision rate ansatz for quantum integrable systems
SciPost Physics, 2020Co-Authors: Takato Yoshimura, Herbert SpohnAbstract:For quantum integrable systems we revisit the currents averaged with respect to a generalized Gibbs Ensemble. In case the system has a self-conserved current, i.e. some current is actually conserved, the symmetry of the current-charge susceptibility matrix implies the conventional collision rate ansatz. The argument is carried out in detail for the Lieb-Liniger model and the Heisenberg XXZ chain. We also explain how from the existence of a boost operator a self-conserved current can be deduced.
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Collision rate ansatz for the classical Toda lattice.
Physical review. E, 2020Co-Authors: Herbert SpohnAbstract:We consider a generalized Gibbs Ensemble of the classical Toda lattice. We establish that the collision rate ansatz follows because (i) the charge-current susceptibility matrix is symmetric and (ii) the stretch current is proportional to the momentum, hence conserved. The method applies also to other integrable many-body systems, either classical or quantum, provided there is a self-conserved current.