A phase diagram of water in single-walled carbon nanotubes at atmospheric pressure is proposed, which summarizes ice structures and their melting points as a function the tube diameter up to 1.7 nm. The investigation based on extensive molecular dynamics simulations over numerous thermodynamic states temperature–diameter plane. Spontaneous freezing analysis 0 K suggest that there exist least nine phases cylindrical space, including those reported by x-ray diffraction studies unreported...

GenIce is an efficient and user‐friendly tool to generate hydrogen‐disordered ice structures. It makes clathrate hydrate structures in various file formats. More than 100 kinds of are preset. Users can install their own crystal structures, guest molecules, formats as plugins. The algorithm certifies that the generated completely randomized networks obeying rule with zero net polarization. © 2017 Authors. Journal Computational Chemistry Published by Wiley Periodicals, Inc.

Molecular dynamics simulations have been performed for hydrogel models of poly(vinyl alcohol) (PVA), methyl ether) (PVME), and poly(N-isopropylacrylamide) (PNiPAM). The spatial distributions stability hydrogen bonds in the vicinity polymer segments are analyzed to investigate properties water which is highly cooperative with surrounding chains. Water−water enhanced around hydrophobic groups especially PVME PNiPAM by hydration. Hydrogen also stabilized hydrophilic PNiPAM. stabilization...

Molecular dynamics simulations were performed to study the phase behavior of a thin film water confined slit nanopore with smooth walls. A first-order water-to-ice freezing transition has been observed. The resulting ice, which is crystal bilayer consisting rows distorted hexagons, does not resemble any ice crystals found so far. contracts upon when confinement load low ( $\ensuremath{\sim}0.5\mathrm{kbar}$) and expands high (10 kbar). residual entropy can be calculated exactly, about half bulk ice.

Open single-wall carbon nanohorns (SWNHs) were compressed repeatedly at 50 MPa to generate a nanocarbon material of high bulk density. TEM observations and Raman spectroscopy revealed significant distortion in the structure SWNHs. The obtained nanostructured disordered exhibits methane storage capacity, reaching 160 cm3/cm3 3.5 303 K. Comparison experimental results with grand canonical Monte Carlo simulations indicates importance adsorption interstitial channels for total capacity generated carbon.

Large local energy fluctuations in liquid water and their physical origin are investigated by using classical molecular dynamics (MD) calculation quenching techniques. Performing a trajectory of 100 ps, it is found that large rotational motions individual molecules, which always associated with potential destabilization 10–20 kcal/mol, occur once about 10 ps. The stabilization the molecules induced cooperative motions. In order to analyze these water, structures quenched minima (called...

The adsorption of guest and kinetic inhibitor molecules on the surface methane hydrate is investigated by using molecular dynamics simulations. We calculate free energy profile for transferring a solute molecule from bulk water to various molecules. Spherical solutes with diameter ∼0.5 nm are significantly stabilized at surface, whereas smaller larger exhibit lower affinity than intermediate size. range attractive force subnanoscale, implying that this has no effect macroscopic mass transfer...

Molecular dynamics simulations have been performed for hydrogel models of poly(vinyl alcohol) (PVA), methyl ether) (PVME), and poly(N-isopropylacrylamide) (PNiPAM). The hydrogen bonds the translational rotational motions water molecules in vicinity polymer segments are analyzed to investigate properties which highly cooperative with surrounding chains. characters hydrophilic groups reflected lifetime bonds, spectral density, etc., examined. mobility is significantly lowered around chains...

The anomalies of supercooled water in thermodynamic response functions at atmospheric pressure, the phase transition between low and high density amorphous ices (LDA HDA), a predicted fragile–strong are accounted for unified manner by reconciling an idea due to Stanley co-workers introducing second critical point separating LDA HDA with conjecture proposed Speedy that is different from normal water, called II. reconciliation made on basis results extensive molecular dynamics simulations...

Molecular dynamics simulations demonstrate that there are at least two classes of quasi-two-dimensional solid water into which liquid confined between hydrophobic surfaces freezes spontaneously and whose hydrogen-bond networks as fully connected those bulk ice. One them is the monolayer ice other bilayer takes either a crystalline or an amorphous form. Here we present phase transformations among liquid, (or crystalline) ice, phases various thermodynamic conditions, then determine curves...

A detailed analysis is made for the dynamical behavior of an individual water molecule in liquid by using a classical molecular dynamics (MD) calculation. It found that there exist very large potential energy fluctuations water; single can exhibit fluctuation order 10∼20 kcal/mol. These be classified into two categories; fast component (10−14–10−13 s) associated with librational motions molecules and slow (10−12–10−11 binding structure changes. Both amplitudes reached up to 10 Due strong...

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTThermodynamic Stability of Hydrates for Ethane, Ethylene, and Carbon DioxideBjorn Kvamme Hideki TanakaCite this: J. Phys. Chem. 1995, 99, 18, 7114–7119Publication Date (Print):May 1, 1995Publication History Published online1 May 2002Published inissue 1 1995https://pubs.acs.org/doi/10.1021/j100018a052https://doi.org/10.1021/j100018a052research-articleACS PublicationsRequest reuse permissionsArticle Views620Altmetric-Citations107LEARN ABOUT THESE...

The crystal structure of [Cu(4,4'-bipyridine) 2(CF 3SO 3) 2] n metal-organic framework (CuBOTf) one-dimensional pore networks after pre-evacuation at 383 K was determined with synchrotron X-ray powder diffraction measurement. Effective nanoporosity the pre-evacuated CuBOTf N 2 adsorption 77 K. experimental H and D isotherms 40 were measured then compared GCMC-simulated using effective nanoporosity. quantum-simulated Feynman-Hibbs potential coincided ones, giving a direct evidence on quantum...

An outstanding compression function for materials preparation exhibited by nanospaces of single-walled carbon nanohorns (SWCNHs) was studied using the B1-to-B2 solid phase transition KI crystals at 1.9 GPa. High-resolution transmission electron microscopy and synchrotron X-ray diffraction examinations provided evidence that nanocrystals doped in nanotube spaces SWCNHs pressures below 0.1 MPa had super-high-pressure B2 structure, which is induced above GPa bulk crystals. This finding...

We report a molecular dynamics simulation demonstrating fast spontaneous liquid-liquid phase separation of water and subsequent slow crystallization to ice. It is found that supercooled separates rapidly into low- high-density domains so as reduce the surface energy in rectangular cell at certain thermodynamic states. The separation, which about two orders magnitude faster than crystallization, suggests possibility observe this phenomenon experimentally.

Bubble formation and the hydration free energy of methane play important roles in hydrate dissociation. The effects methanol NaCl on them are investigated using molecular dynamics simulations.

We investigate the mechanism of a typical kinetic hydrate inhibitor (KHI), polyvinylcaprolactam (PVCap), which has been applied to prevent plugs from forming in gas pipe lines, using molecular dynamics simulations crystal growth ethylene oxide hydrate. Water-soluble is chosen as guest species avoid problems associated with presence phase simulation cell such slow growth. A PVCap dodecamer adsorbs irreversibly on surface grows at supercooling 3 K when hydrophobic part two pendent groups are...

Molecular dynamics simulations of the dissociation methane hydrate in aqueous NaCl solutions are performed. It is shown that accelerated by formation bubbles both and pure water. We find two significant effects on kinetics NaCl. One slowing down an early stage before bubble formation, another swift enhances dissociation. These arise from low solubility solution, which gives rise to a nonuniform spatial distribution solvated phase. also demonstrate form near interface dense proceeds...

Most classical nonpolarizable ion potential models underestimate the solubility values of NaCl and KCl in water significantly. We determine Lennard-Jones parameters Na+, K+, Cl– that reproduce as well hydration free energy dilute aqueous solutions for three models, SPC/E, TIP3P, TIP4P/2005. The ion–oxygen distance solution cation–anion salt are also considered parametrization. In addition to target properties, enthalpy, entropy, self-diffusion coefficient, coordination number, lattice...