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Full-Text Articles in Physical Sciences and Mathematics
Monte Carlo Simulation Of Homogeneous Binary Vapor–Liquid Nucleation: Mutual Enhancement Of Nucleation In A Partially Miscible System, S. Yoo, K.J. Oh, Xiao Cheng Zeng
Monte Carlo Simulation Of Homogeneous Binary Vapor–Liquid Nucleation: Mutual Enhancement Of Nucleation In A Partially Miscible System, S. Yoo, K.J. Oh, Xiao Cheng Zeng
Xiao Cheng Zeng Publications
Gibbs free energy of ij-cluster formation ΔGij is obtained via the relation nij=Ne-ΔGij /kBT, where N is the number of molecules in the system, T is temperature, and kB is the Boltzmann constant. The saddle point on the free energy surface ΔGij versus i and j provides a measure of the activation barrier to nucleation ΔG *. A statistical mechanical formula of ΔGij is derived based on the physical-cluster theory of nucleation, and from which a molecular interpretation of ΔGij …
Energetics And Cooperativity In Three-Center Hydrogen Bonding Interactions. Ii. Intramolecular Hydrogen Bonding Systems, Ruben D. Parra, Bing Gong, Xiao Cheng Zeng
Energetics And Cooperativity In Three-Center Hydrogen Bonding Interactions. Ii. Intramolecular Hydrogen Bonding Systems, Ruben D. Parra, Bing Gong, Xiao Cheng Zeng
Xiao Cheng Zeng Publications
High level ab initio calculations have been carried out on a number of intramolecular two- and three-center H-bonding structures containing the amide motif, NHC=O. These structures serve as model systems for probing the stability of intramolecular three-center H bonds of the type A1HA2. Particular attention is given to cooperative effects in the three-center H-bonding structures. A systematic assessment of cooperativity for intramolecular H-bonding systems is presented.
Energetics And Cooperativity In Three-Center Hydrogen Bonding Interactions. I. Diacetamide-X Dimers .X=Hcn, Ch3Oh., Ruben D. Parra, Makoto Furukawa, Bing Gong, Xiao Cheng Zeng
Energetics And Cooperativity In Three-Center Hydrogen Bonding Interactions. I. Diacetamide-X Dimers .X=Hcn, Ch3Oh., Ruben D. Parra, Makoto Furukawa, Bing Gong, Xiao Cheng Zeng
Xiao Cheng Zeng Publications
High level ab initio calculations are carried out on diacetamide–X (DA–X) dimers, X=HCN, CH3OH. The dimers are used as model systems to investigate the energetics and cooperative phenomomena in intermolecular three-center hydrogen-bond (H-bond) interactions relative to two-center H-bond interactions. The trans–trans conformer of diacetamide is chosen as a suitable model for intermolecular three-center H bonding where one H atom is interacting with two acceptor atoms. The proton–acceptor atoms are rigidly held in the same molecule. For both model systems, it is found that the calculated interaction energy per H bond is appreciably smaller in the three-center than in …
Formation Of Ordered Ice Nanotubes Inside Carbon Nanotubes, Kenichiro Koga, G. T. Gao, Hideki Tanaka, Xiao Cheng Zeng
Formation Of Ordered Ice Nanotubes Inside Carbon Nanotubes, Kenichiro Koga, G. T. Gao, Hideki Tanaka, Xiao Cheng Zeng
Xiao Cheng Zeng Publications
Following their discovery, carbon nanotubes have attracted interest not only for their unusual electrical and me-chanical properties, but also because their hollow interior can serve as a nanometre-sized capillary, mould, or template in material fabrication. The ability to en¬capsulate a material in a nanotube also offers new possibili¬ties for investigating dimensionally confined phase transi¬tions . Particularly intriguing is the conjecture that matter within the narrow confines of a carbon nanotube might ex¬hibit a solid–liquid critical point beyond which the distinc¬tion between solid and liquid phases disappears. This unusual feature, which cannot occur in bulk material, would allow for the direct …
Molecular Dynamics Simulation Of Supersaturated Vapor Nucleation In Slit Pore. Ii. Thermostatted Atomic-Wall Model, K.T. Kholmurodov, K. Yasuoka, Xiao Cheng Zeng
Molecular Dynamics Simulation Of Supersaturated Vapor Nucleation In Slit Pore. Ii. Thermostatted Atomic-Wall Model, K.T. Kholmurodov, K. Yasuoka, Xiao Cheng Zeng
Xiao Cheng Zeng Publications
Molecular dynamics simulations of nucleation of a supersaturated Lennard-Jones vapor in slit nanopores are carried out. In this study we extend a previous work [K. Yasuoka, G. T. Gao, and X. C. Zeng, J. Chem. Phys. 112, 4279 (2000)] in that the walls of the slit are treated as actual atomic walls serving as both the confining solid surfaces and a thermostat. The walls are fixed in place in a fcc lattice structure and wall atoms are subjected to a stiff biharmonic potential thereby bounded to lattice sites. The two walls of the slit have an identical surface [fcc (100)], …
Nucleation Of Water And Methanol Droplets On Cations And Anions: The Sign Preference, K.J. Oh, G.T. Gao, Xiao Cheng Zeng
Nucleation Of Water And Methanol Droplets On Cations And Anions: The Sign Preference, K.J. Oh, G.T. Gao, Xiao Cheng Zeng
Xiao Cheng Zeng Publications
The barrier height to cation- and anion-induced nucleation to produce water and methanol droplets are calculated by means of an umbrella-sampling Monte Carlo method. The computer simulation corroborates the century-old finding of Wilson that the anion is a better nucleator to produce water droplets than the cation having the same magnitude of charge, even without the presence of external electric field. The simulation also shows that the cation is a better nucleator to produce methanol droplets than the anion.
Effect Of Carrier-Gas Pressure On Barrier To Nucleation: Monte Carlo Simulation Of Water/Nitrogen System, K.J. Oh, Xiao Cheng Zeng
Effect Of Carrier-Gas Pressure On Barrier To Nucleation: Monte Carlo Simulation Of Water/Nitrogen System, K.J. Oh, Xiao Cheng Zeng
Xiao Cheng Zeng Publications
Carrier gases are used in most nucleation experiments for releasing the latent heat generated during vapor condensation. In the analysis of experimental data it is often assumed that the carrier gas is inert and would not participate in the nucleation process of the target gas. Several recent nucleation experiments show that the influence of carrier gases to nucleation rate is not negligible under certain conditions. To gain more insight into the carrier-gas effect, we carry out Monte Carlo simulation to compute the free energy of formation of water clusters in the presence of a nitrogen carrier gas. At fixed temperature …
Effects Of External Electric Field On The Interfacial Properties Of Weakly Dipolar Fluid, V.B. Warshavsky, T.V. Bykov, Xiao Cheng Zeng
Effects Of External Electric Field On The Interfacial Properties Of Weakly Dipolar Fluid, V.B. Warshavsky, T.V. Bykov, Xiao Cheng Zeng
Xiao Cheng Zeng Publications
In the framework of modified mean-field density-functional theory, effects of a uniform electric field on the interfacial properties of a model dipolar fluid [Teixeira and Telo da Gama, J. Phys.: Condens. Matter 3, 111 (1991)] are studied. Both density and orientational order-parameter profiles of the planar vapor-liquid interface are obtained as a function of the field strength. For the dipolar fluids with reduced dipole moment μ0*0*E*/T*!1) can shift the surface tension by few percent. We also find that the electric field actually reduces the thermodynamical surface tension but enhances the mechanical surface …