Archive for the ‘researches 5’ Category
Wednesday, March 19th, 2008
Short-time transport properties in dense suspensions: From neutral to charge-stabilized colloidal spheres.
We present a detailed study of short-time dynamic properties in concentrated suspensions of charge-stabilized and of neutral colloidal spheres. The particles in many of these systems are subject to significant many-body hydrodynamic interactions. A ...
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Wednesday, March 19th, 2008
The electronic structure of the four nucleotide bases in DNA, of their stacks, and of their homopolynucleotides in the absence and presence of water.
Using the ab initio Hartree-Fock crystal orbital method in its linear combination of atomic orbital form, the energy band structure of the ...
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Wednesday, March 19th, 2008
Theoretical study of the three-phase contact line and its tension in adsorbed colloid-polymer mixtures.
We perform a theoretical study of the three-phase contact line and the line tension in an adsorbed colloid-polymer mixture near a first-order wetting transition, employing an interface displacement model. We use a ...
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Wednesday, March 19th, 2008
Molecular dynamics of immiscible fluids in chemically patterned nanochannels.
Molecular dynamics simulations of chain molecules are used to elucidate physical phenomena involved in flows of dense immiscible fluids in nanochannels. We first consider a force driven flow in which the channel walls are homogeneous and wetting ...
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Wednesday, March 19th, 2008
Segmental versus chain dynamics of linear polymers.
Segmental dynamics of relatively short linear polymers are discussed in terms of two distinct contributions, one related to the local segmental motion (alpha relaxation) and the other to polymer-specific effects that reflect Brownian dynamics of the polymer under chain ...
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Wednesday, March 19th, 2008
An investigation of the sodium patterning in Na(x)CoO(2) (0.5</=x</=1) by density functional theory methods.
Extensive experimental work has been carried out to characterize the stable Na-vacancy ordering patterns at various compositions of layered Na(x)CoO(2). However, contradictions and debates prevail in the literature, particularly at high Na ...
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Wednesday, March 19th, 2008
Density functional theory studies of inorganic metallocene multidecker V(n)(P(6))(n+1) (n=1-4) sandwich clusters.
Motivated by the synthesis of the first entirely inorganic metallocene sandwich ion [eta(5)-Ti-(P(5))(2)](2-) [E. Urnezius et al. Science 295, 832 (2002)], we have designed a new inorganic metallocene sandwich [eta(6)-V-(P(6))(2)] and multidecker sandwich clusters ...
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Wednesday, March 19th, 2008
Nematic ordering and defects on the surface of a sphere: A Monte Carlo simulation study.
We examine the ordering of hard rods on the surface of a sphere using computer simulations. As predicted by previous theories of thin nematic shells we observe four s=+1/2 defects. However, ...
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Wednesday, March 19th, 2008
The interfacial properties of MgCl(2) thin films grown on Si(111)7x7.
Photoelectron spectroscopy with synchrotron radiation and low energy electron diffraction (LEED) were used in order to study the MgCl(2)Si(111) system. At submonolayer coverage of MgCl(2), a new LEED pattern was observed corresponding to a (3x3)R30 degrees ...
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Wednesday, March 19th, 2008
Nonadiabaticity in the iron bcc to hcp phase transformation.
Iron is known to undergo a pressure-induced phase transition from the ferromagnetic (FM) body-centered-cubic (bcc) alpha-phase to the nonmagnetic (NM) hexagonal-close-packed (hcp) epsilon-phase, with a large observed pressure hysteresis whose origin is still a matter of debate. ...
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Wednesday, March 19th, 2008
NO(2) dissociation on Ag(111) revisited by theory.
NO(2) dissociation on Ag(111) is investigated with first-principles calculations. For single NO(2) molecules, a high adsorption potential energy is found to prohibit dissociation. This result is surprising as experiments indicate dissociation at low temperatures. Neither entropy effects nor irregularities ...
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Wednesday, March 19th, 2008
The adsorption and desorption of ethanol ices from a model grain surface.
Reflection absorption infrared spectroscopy (RAIRS) and temperature programed desorption (TPD) have been used to probe the adsorption and desorption of ethanol on highly ordered pyrolytic graphite (HOPG) at 98 K. RAIR spectra for ethanol ...
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Wednesday, March 19th, 2008
The effects of electronic structure and charged state on thermodynamic properties: An ab initio molecular dynamics investigations on neutral and charged clusters of Na(39), Na(40), and Na(41).
In this paper we explore the effects of the electronic structure, the charge state, and the nature of energy ...
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Wednesday, March 19th, 2008
The dissociation and equation of state of dense fluid oxygen at high pressures and high temperatures.
The dissociation, pressure, and internal energy of dense fluid oxygen at high temperatures and densities have been calculated from the free-energy functions using the self-consistent fluid variational theory. In this ...
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Wednesday, March 19th, 2008
Local biaxiality in cholesteric liquid crystals from the surface interaction model.
The feature of local biaxiality of the orientational order in twisted nematics and cholesteric liquid-crystalline phases is faced by modeling the mean field orientational potential on the basis of the surface interaction model [A. Ferrarini, ...
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Wednesday, March 19th, 2008
Phase behavior of density-dependent pair potentials.
Phase diagram is calculated by a recently proposed third-order thermodynamic perturbation theory (TPT) for fluid phase and a recently proposed first-order TPT for solid phases; the underlying interparticle potential consists of a hard sphere repulsion and a perturbation tail of ...
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Wednesday, March 19th, 2008
The stability of a salt-free colloidal dispersion.
The electrical potential for the case of two identical, planar parallel particles immersed in a salt-free medium, where the ionic species in the counterions come solely from those that dissociated from the surfaces, is evaluated. Analytical expressions for the ...
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Wednesday, March 19th, 2008
New topic of supercritical fluids: Local activity coefficients of supercritical solvent and cosolvent around solute.
The study of inhomogeneity in supercritical fluids (SCFs) is of great importance. In this work, we propose the concept of local activity coefficients in supercritical (SC) solutions, which link thermodynamics and ...
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Wednesday, March 19th, 2008
Factors influencing deformation stability of binary glasses.
A possible mechanism of strain accommodation in large deformation of glasses is crystallization; deformation stability is a measure of the resistance of glasses to crystallization. We study the effect of atomic size ratio and atomic stiffness parameter (related to ...
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Wednesday, March 19th, 2008
Hydrophobic solvation of Gay-Berne particles in modified water models.
The solvation of large hydrophobic solutes, modeled as repulsive and attractive Gay-Berne oblate ellipsoids, is characterized in several modified water liquids using the SPC/E model as the reference water fluid. We find that small amounts of attraction ...
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Wednesday, March 19th, 2008
Three-point frequency fluctuation correlation functions of the OH stretch in liquid water.
Characterizing the dynamics of the OH stretch in isotopically substituted liquid water (HOD in D(2)O) in terms of three-point frequency fluctuation correlation functions and joint probability densities shows that dynamics during hydrogen bond rearrangements ...
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Wednesday, March 19th, 2008
Intermediate motions as studied by solid-state separated local field NMR experiments.
In this report, the application of a class of separated local field NMR experiments named dipolar chemical shift correlation (DIPSHIFT) for probing motions in the intermediate regime is discussed. Simple analytical procedures based on the ...
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Wednesday, March 19th, 2008
New contributions to the photophysical model for all-trans-polyenes from ttbP4, a nonphotolabile octatetraene.
All-trans-octatetraene 3,10-di(tert-butyl)-2,2,11,11-tetramethyl-3,5,7,9-dodecatetraene emits fluorescence in three different regions of the visible spectrum. Thus, it produces an extremely weak emission in the gas phase that can hardly be detected in the condensed phase; such ...
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Wednesday, March 19th, 2008
Bond connectivity measured via relaxation-assisted two-dimensional infrared spectroscopy.
The relaxation-assisted two-dimensional infrared (RA 2DIR) method is a novel technique for probing structures of molecules, which relies on vibrational energy transport in molecules. In this article we demonstrate the ability of RA 2DIR to detect the bond ...
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Wednesday, March 19th, 2008
Structural precursor to freezing: An integral equation study.
Recent simulation studies have drawn attention to the shoulder which forms in the second peak of the radial distribution function of hard spheres at densities close to freezing and which is associated with local crystalline ordering in the ...
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