STRUCTURE AND DYNAMICS CARBOHYDRATE-WATER-SALT SOLUTIONS AS DERIVED FROM MOLECULAR DYNAMICS SIMULATIONS

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Orbital overlap effects in electron transfer reactions across a metal nanowire/electrolyte solution interface

In this paper, we report on calculations of the orbital overlap between Fe(III) and Cr(III) aquacomplexes and different electrode surfaces: Cu(111), Ag (111), Au(111), Pt(111), and corresponding monatomic wires. The electronic structure of the monocrystalline surfaces and nanowires are described in terms of the electronic spillover and density of electronic states at the Fermi level obtained from periodic density functional theory (DFT) calculations. The transmission coefficients (κ) characterizing the first stage of outer-sphere electron transfer for the reduction of aquacomplexes are calculated on the basis of Landau–Zener theory as a function of electrode–reactant separation; the electronic transmission coefficients for the [Cr(H2O)6]3+/2+ redox couple were found to be smaller than those for [Fe(H2O)6]3+/2+. Two different intervals can be clearly distinguished for Cu, Au and Pt: “a catalytic region”, where κ(wire) > κ(Me slab) and “an inhibition region”, where κ(wire) < κ(Me slab). A similar behavior exhibits the coupling constant estimated for a hydrogen atom adsorbed at the Au(111) surface and the Au monatomic wire. These effects originate from some specific features of electronic density profile for metal nanowires: at short distances the electronic density of nanowires is higher compared with the (111) metal surfaces, while at larger separations it decreases more sharply.Fil: Nazmutdinov, Renat R.. Kazan National Research Technological University; RusiaFil: Berezin, Alexander S.. Kazan National Research Technological University; RusiaFil: Soldano, Germán. Universitat Ulm; Alemania. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Schmickler, Wolfgang. Universitat Ulm; Alemani

Dipole moments of organophosphorus compounds. 16. Conformations of trimethylsilyl groups in some phosphites, phosphates, and phosphonates

1. A study has been made of the dipole moments, Kerr constants, and IR spectra of silicon-containing phosphites, phosphates, and phosphonates. 2. The silicon-containing phosphates and phosphonates exist as equilibrium mixtures of various conformers, the predominant form being that in which the P=0 (S, Se) and (CH3)3SiO groups are in cis orientation. 3. The trimethylsilyl group preferentially occupies a gauche position with respect to the unshared electron pair of the phosphorus atom in compounds containing phosphorus in three-coordination. © 1978 Plenum Publishing Corporation

Dissociative adsorption of water molecules on uncharged surfaces of indium(111) and gallium

A possible mechanism of dissociative adsorption (DA) of water on the (111) surface of indium and liquid gallium is investigated within a cluster model for metal using a density functional method (B3LYP). The adsorption interaction of H and O atoms and OH group with these metals is studied. The free energy of DA of H2 and O2 molecules is calculated. An analysis of DA is performed both for the case of the metal/vacuum interface and with allowance made for solvation effects within a continuum approach. According to quantum-chemical calculations, DA of water on the In(111) surface is more thermodynamically probable than on gallium. In the case of indium, DA with the participation of a water dimer may have a smaller activation energy compared with DA of monomer H2Oads. The data obtained are used to interpret the experimentally observed nonmonotonous dependence of the work function for indium and gallium on the partial pressure of water vapor. The hypothesis about the origin of the absorption band in electroreflectance spectra for the gallium/aqueous solution interface as a result of the electron transfer from an adsorbed water molecule into the metal's conduction band is confirmed

Dissociative adsorption of water molecules on uncharged surfaces of indium(111) and gallium

A possible mechanism of dissociative adsorption (DA) of water on the (111) surface of indium and liquid gallium is investigated within a cluster model for metal using a density functional method (B3LYP). The adsorption interaction of H and O atoms and OH group with these metals is studied. The free energy of DA of H2 and O2 molecules is calculated. An analysis of DA is performed both for the case of the metal/vacuum interface and with allowance made for solvation effects within a continuum approach. According to quantum-chemical calculations, DA of water on the In(111) surface is more thermodynamically probable than on gallium. In the case of indium, DA with the participation of a water dimer may have a smaller activation energy compared with DA of monomer H2Oads. The data obtained are used to interpret the experimentally observed nonmonotonous dependence of the work function for indium and gallium on the partial pressure of water vapor. The hypothesis about the origin of the absorption band in electroreflectance spectra for the gallium/aqueous solution interface as a result of the electron transfer from an adsorbed water molecule into the metal's conduction band is confirmed

Dissociative adsorption of water molecules on uncharged surfaces of indium(111) and gallium

A possible mechanism of dissociative adsorption (DA) of water on the (111) surface of indium and liquid gallium is investigated within a cluster model for metal using a density functional method (B3LYP). The adsorption interaction of H and O atoms and OH group with these metals is studied. The free energy of DA of H2 and O2 molecules is calculated. An analysis of DA is performed both for the case of the metal/vacuum interface and with allowance made for solvation effects within a continuum approach. According to quantum-chemical calculations, DA of water on the In(111) surface is more thermodynamically probable than on gallium. In the case of indium, DA with the participation of a water dimer may have a smaller activation energy compared with DA of monomer H2Oads. The data obtained are used to interpret the experimentally observed nonmonotonous dependence of the work function for indium and gallium on the partial pressure of water vapor. The hypothesis about the origin of the absorption band in electroreflectance spectra for the gallium/aqueous solution interface as a result of the electron transfer from an adsorbed water molecule into the metal's conduction band is confirmed

STRUCTURE AND DYNAMICS CARBOHYDRATE-WATER-SALT SOLUTIONS AS DERIVED FROM MOLECULAR DYNAMICS SIMULATIONS

36-3