Search for: self-diffusion-coefficient
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    Investigation of a new mean temperature-dependent potential energy function for methane and its use for the prediction of transport properties

    , Article Molecular Physics ; Volume 105, Issue 10 , 2007 , Pages 1453-1463 ; 00268976 (ISSN) Nahaly, M ; Parsafar, G. A ; Goharshadi, E. K ; Sharif University of Technology
    In this work an improved mean potential energy function for the interaction of an isolated pair of methane is obtained, from which the non-equilibrium properties of methane at zero pressure limit are calculated, accurately. The potential energy function of 21 different fixed orientations of (CH4)2 dimer has been obtained via the coupled cluster method. In order to obtain a mean potential energy function, the Boltzmann-average of the obtained potentials of the selected fixed orientations has been used. Unlike the full potential energy surface with the angle-dependent, the parameters of the mean potential are found to be temperature-dependent. The mean potential energy function is fitted well... 

    Computation of some thermodynamic properties of nitrogen using a new intermolecular potential from molecular dynamics simulation

    , Article Chemical Physics ; Volume 358, Issue 3 , 2009 , Pages 185-195 ; 03010104 (ISSN) Kafshdar Goharshadi, E ; Abbaspour, M ; Namayandeh Jorabchi, M ; Nahali, M ; Sharif University of Technology
    A new pair-potential energy function of nitrogen has been determined via the inversion of reduced viscosity collision integrals and fitted to obtain an analytical potential form. The pair-potential reproduces the second virial coefficient, viscosity, thermal conductivity, self-diffusion coefficient, and thermal diffusion factor of nitrogen in a good accordance with experimental data over wide ranges of temperatures and densities. We have also performed the molecular dynamics simulation to obtain pressure, internal energy, heat capacity at constant volume, and self-diffusion coefficient of nitrogen at different temperatures and densities using our calculated pair-potential and some other... 

    Properties of Nafion Under Uniaxial Loading at Different Temperatures: A Molecular Dynamics Study

    , Article Polymer - Plastics Technology and Engineering ; Volume 54, Issue 8 , 2015 , Pages 806-813 ; 03602559 (ISSN) Ozmaian, M ; Naghdabadi, R ; Sharif University of Technology
    Taylor and Francis Inc  2015
    Nafion membrane encounters many different thermal conditions and mechanical loadings because of its wide range of applications as a proton exchange membrane (PEM). Molecular dynamics simulation of hydrated Nafion at different temperatures is carried out to investigate the alteration of the physical properties of Nafion under uniaxial loading over a wide range of temperatures. According to the simulation results, increase of the temperature reduces the yield stress. The results also show that the polymer chains ordering increases the glass transition temperature and enhances the self-diffusion coefficient of water in hydrated Nafion. Comparisons show that the elastic modulus and viscosity... 

    Study of self-diffusion in two binary solutions, glycerol-water and methanol-water using diffusion-ordered spectroscopy

    , Article Scientia Iranica ; Volume 23, Issue 3 , 2016 , Pages 1175-1183 ; 10263098 (ISSN) Fadaei, E ; Tafazzoli, M ; Sharif University of Technology
    Sharif University of Technology 
    The concentration and temperature behaviors of the self-diffusion coefficient were analyzed in glycerol-water and methanol-water solutions using Diffusion-Ordered Spectroscopy (DOSY) experiment. Our results indicate that the self-diffusion coefficient dips with increasing concentration and decreasing temperature. The concentration behavior shows that there is hydrogen bond interaction between water and alcohol, which declines the self-diffusion coefficients of both in the aqueous binary mixtures. The self-diffusion activation energies were estimated 13.6, 29.4, and 32.8 (kJ/mol) for methanol and 24.8, 25.5, and 27.6 (kJ/mol) for water in the methanol-water solutions with 0.03, 0.10, and 0.20...