We extend the density functional theory of nonuniform fluids to cases systems composed polyatomic species. By method Legendre transforms, one demonstrates existence a free energy where densities refer locations interaction sites (not full molecular coordinates). A variational principle for is derived. The methodology retains nearly all mathematical simplicity traditional atomic fluids. Thus, it may provide practical route deriving mean field theories assembly and phase transitions in complex...

With the density functional theory outlined in paper I, we address and formally solve nonlinear inversion problem associated with identifying entropy for systems bonding constraints. this development, derive a integral equation average site fields of polyatomic system. When external potential are set to zero, represents mean field symmetry breaking thus phase transformations systems. In united atom limit where intramolecular interaction sites become coincident, becomes identical that...

We studied the effect of side reactions on reversibility epoxy with thermoreversible Diels–Alder (DA) cycloadducts based furan and maleimide chemistry. The most common reaction is homopolymerization which introduces irreversible crosslinking in network adversely affecting recyclability. main challenge that temperatures at can occur are approximately same as retro-DA (rDA) depolymerize networks. Here we conducted detailed studies three different strategies to minimize reaction. First,...

Polymer-RISM (Reference-interaction-site-model) theory is used to examine the local structure of a dense polyethylene melt near freezing point. Predictions for static factor are found be in quantitative agreement with new x-ray diffraction data obtained at 430 K and 1 atm.

Reversible epoxies using the Diels–Alder chemistry enables recycling processes through depolymerizing polymer at higher temperature and then repolymerizing upon cooling. Compared to conventional bulk heating, photothermal heating can save time resource and, consequently, reduce costs reach an elevated for of reversible epoxies. In previous studies, self‐healing cracks reattachments two broken pieces have been presented a laser; however, sample as whole is not feasible by such point light...

BACKGROUND Age-related facial volume loss results from changes in skin, muscle, and fat distribution, leading to sagging contour alterations. Traditional restoration techniques, such as dermal fillers, carry risks require skilled application. Facial muscle electrical stimulation combined with synchronized radiofrequency (RF) offers a noninvasive alternative. OBJECTIVE This study evaluates the volumetric effects of RF for rejuvenation. MATERIALS AND METHODS A retrospective analysis was...

We hypothesize that the shift of glass transition temperature polymers in confined geometries can be largely attributed to inhomogeneous density profile liquid. Accordingly, we assume state approximated by Tg a corresponding homogeneous, bulk polymer, but at equal average system. Simple models based on this hypothesis give results which are agreement with experimental measurements liquids.

The density functional theory of freezing is used to study the liquid crystal phase transition in hardsphere and Lennard-Jones systems. An important step calculation parametrization solid average single particle ρ(r). In this work two popular parametrizations are compared. first method a general Fourier decomposition periodic which amplitude each (non-symmetry-related) component treated as an independent parameter. second parametrization, more restrictive but easier implement, approximates...

We present the first implementation of our density functional theory [J. Chem. Phys. 85, 5971, 5977 (1986)] to investigate a fluid–solid phase transition. In this theory, designed specifically for polyatomic systems, entropy with bonding constraints is treated exactly, and approximations are generated by truncating expansions intermolecular interaction part free-energy functional. examine resulting from quadratic truncation free energy, determine diagram hard dumbbell molecules. The results...

We modeled the effects of temperature, degree polymerization, and surface coverage on equilibrium structure tethered poly(N-isopropylacrylamide) chains immersed in water. employed a numerical self-consistent field theory where experimental phase diagram was used as input to theory. At low temperatures, composition profiles are approximately parabolic extend into solvent. In contrast, at temperatures above LCST bulk solution, polymer collapsed near surface. The layer thickness effective...

Previous applications of density functional (DF) theory required a single chain Monte Carlo simulation to be performed within self-consistent loop. In the current work, methodology is developed which permits taken out iterative Consequently, calculation self-consistent, medium-induced potential, or field, decoupled from simulation. This approach different densities, forms UM(r), and wall–polymer interactions investigated The increase in computational efficiency immense.

Reversible work, also known as the potential of mean force, is used to map explicit atom (EA) onto united (UA) potentials for CH, CH2, CH3, and CH4 sites. These UA are found be temperature dependent described by stretched exponential-6 functions. Although this fairly dissimilar Lennard-Jones 6−12 potential, one may mapped other requiring that second virial coefficients locations minimum equal two forms. When done, good agreement with standard found.

We employ density functional methods to derive an integral equation for the two-point intermolecular correlation function in molecular liquids. This radial distribution is expressed as a two molecule average over Boltzmann factor involving ‘‘bare’’ site–site interaction, plus pairwise additive, intermolecular, medium induced potential which mimics remaining molecules system. theory formally exact low limit. While valid general large and polymer liquids, we demonstrate its use here case of...

Polyatomic density functional theory was used to model tridecane chains near a hard wall under melt conditions. Polymer reference interaction site (PRISM) liquid state provided the bulk structure input for functional. The profile, fractional distribution of sites, and variation end-to-end separation as function distance from contact were calculated, excellent agreement with results full multichain simulation found.

The athermal contribution to the pressure of polyethylene is investigated via integral equations and mean field generalized Flory-type theories. molecules are modeled as fused-hard-sphere chains with fixed bond lengths angles; torsional rotations treated rotational isomeric state approximation literature values for trans–gauche energies. hard sphere diameter obtained by matching structure factor predictions polymer reference interaction site model (PRISM) theory data from wide-angle...

Density functional theory (DFT) was used to study polymer chains, tethered a surface and in the presence of solvent. For reasons computational practicality, it is common practice remove explicit solvent molecules from problem. Contact made with two such models, which we call “implicit-solvent” “continuum-solvent” approximations. First, DFT applied chains an implicit Using equation state bead–spring as input, found excellent agreement density profiles obtained molecular dynamics simulations...

Molecular density-functional theory is extended to address the crystallization of chemically realistic polymers. The polymer (RISM) reference interaction site model integral-equation approach employed calculate liquid-state structural information required as ‘‘input’’ into our theory. single-chain structure described by rotational isomeric state model, and accuracy both theoretically calculated liquid structures have been verified direct comparison with Monte Carlo simulation x-ray...

Athermal, tethered chains are modeled with density functional (DFT) theory for both the explicit solvent and continuum cases. The structure of DFT is shown to reduce self-consistent-field in incompressible limit where there symmetry between monomer, single-chain-mean-field (SCMF) limit. We show that by careful selection reference ideal systems theory, self-consistent numerical solutions can be obtained, thereby avoiding single chain Monte Carlo simulation SCMF theory. On long length scales,...

We present a new real space Newton-based computational approach to computing the properties of inhomogeneous polymer systems with density functional theory (DFT). The DFT is made computationally efficient by modeling polymers as freely jointed chains and obtaining direct correlation functions from reference interaction site model calculations. code we can solve equations in up three dimensions using parallel implementation. In addition describe our implementation an arc-length continuation...

Views Icon Article contents Figures & tables Video Audio Supplementary Data Peer Review Share Twitter Facebook Reddit LinkedIn Tools Reprints and Permissions Cite Search Site Citation John D. McCoy, Steven W. Rick, A. J. Haymet; Freezing of quantum liquids. Chem. Phys. 15 April 1989; 90 (8): 4622–4623. https://doi.org/10.1063/1.456600 Download citation file: Ris (Zotero) Reference Manager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Dropdown Menu input auto suggest...

Views Icon Article contents Figures & tables Video Audio Supplementary Data Peer Review Share Twitter Facebook Reddit LinkedIn Tools Reprints and Permissions Cite Search Site Citation Douglas B. Adolf, Robert S. Chambers, Jesse Flemming, Joanne Budzien, John McCoy; Potential energy clock model: Justification challenging predictions. J. Rheol. 1 May 2007; 51 (3): 517–540. https://doi.org/10.1122/1.2716442 Download citation file: Ris (Zotero) Reference Manager EasyBib Bookends Mendeley Papers...

Simple tangent, hard site chains near a wall are modeled with density functional (DF) theory that uses the direct correlation function, c(r), as its “input.” Two aspects of this DF focused upon: (1) consequences variations in c(r)’s detailed form; and (2) correct way to introduce c(r) into formalism. The most important aspect is found be integrated value, ĉ(0). Indeed, it appears that, for fixed ĉ(0), all reasonable guesses shape result surprisingly similar distributions, ρ(r). Of course,...

X-Ray diffraction data on n-alkane fluids ranging from n-butane to polyethylene are analysed yield the relative contributions intra- and inter-molecular scattering. The intramolecular calculated an exact rotational-isomeric-state model at short length scales, approximated by a semiflexible chain global scales. With increasing length, intermolecular pair distribution functions show general decrease in short-range structure along with predicted self-screening, or de Gennes ‘correlation hole’,...