scholarly journals The Radial Distribution Functions of Water as Derived from Radiation Total Scattering Experiments: Is There Anything We Can Say for Sure?

2013 ◽  
Vol 2013 ◽  
pp. 1-67 ◽  
Author(s):  
A. K. Soper
Keyword(s):  
Radial Distribution ◽  
Water Structure ◽  
Distribution Functions ◽  
Scattering Data ◽  
Radial Distribution Functions ◽  
Radiation Scattering ◽  
Neutron Data ◽  
Simulation Tools ◽  
Novel Method

The present paper reviews the investigation of ambient water structure and focusses in particular on the determination of the radial distribution functions of water from total experimental radiation scattering experiments. A novel method for removing the inelastic scattering from neutron data is introduced, and the effect of Compton scattering on X-ray data is discussed. In addition the extent to which quantum effects can be discerned between heavy and light water is analysed against these more recent data. It is concluded that, with the help of modern data analysis and computer simulation tools to interrogate the scattering data, a considerable degree of consistency can be obtained between recent and past scattering experiments on water. That consistency also gives a realistic estimate of the likely uncertainties in the extracted radial distribution functions, as well as offering a benchmark against which future experiments can be judged.

Modelling of Partial and Total Radial Distribution Functions of Amorphous Ni2B Using Reverse Monte Carlo Simulation

1991 ◽  
Vol 46 (1-2) ◽  
pp. 69-72 ◽  
Author(s):  
Läszlö Pusztai
Keyword(s):  
Monte Carlo Simulation ◽  
Monte Carlo ◽  
Radial Distribution ◽  
Metallic Glasses ◽  
Distribution Functions ◽  
Radial Distribution Functions ◽  
Reverse Monte Carlo ◽  
Reverse Monte Carlo Simulation ◽  
Novel Method ◽  
Initial Results

AbstractThe use of Reverse Monte Carlo simulation, a novel method of structural modelling, looks very promising for the case of metallic glasses. In this paper initial results are shown for glassy Ni2B, using experimental radial distribution functions as input information.

Thermodynamics and structure of the {water + methanol} system viewed from three simple additive pair-wise intermolecular potentials based on the rigid molecule approximation

2010 ◽  
Vol 75 (5) ◽  
pp. 617-635 ◽  
Author(s):  
Ana Dopazo-Paz ◽  
Paula Gómez-Álvarez ◽  
Diego González-Salgado
Keyword(s):  
Radial Distribution ◽  
Pure Water ◽  
Water System ◽  
Water Structure ◽  
Distribution Functions ◽  
Radial Distribution Functions ◽  
Intermolecular Potentials ◽  
Excess Molar Enthalpy ◽  
Metropolis Monte Carlo ◽  
Partial Success

The ability of three additive pair-wise intermolecular potentials to reproduce both thermodynamics and structure of the {methanol + water} system is analysed in detail using Metropolis Monte Carlo simulations. The three potentials were constructed using the OPLS model for methanol and for water, in each case, were used the TIP4P, TIP4P/2005, and TIP4P/ice, respectively. For all the potentials, the Lorentz–Berthelot combining rule was considered to calculate water–methanol cross interactions. A wide set of first- and second-order excess thermodynamic derivatives and the site–site radial distribution functions were chosen for the study. The properties were obtained at room conditions over the whole composition range and were critically compared with selected experimental data. It turns out that the simulation results of the different potentials show no qualitative differences in the radial distribution functions whereas that the excess thermodynamic properties usually decreases in the sense TIP4P > TIP4P/2005 > TIP4P/ice. The best agreement with the experiments has been found for the potential that uses the TIP4P/2005 model which demonstrates that using potentials based on phase diagram calculations significantly improve the results for this mixture. However, even in this case only partial success was found. As regards thermodynamics, it has been detected problems to describe the excess compressibility and the excess molar enthalpy. As regards structure, although it predicts clustering of methanol molecules via methyl groups after mixing, it was unable to reproduce the preservation of the pure water structure in the mixture, a well-established phenomenon observed by neutron scattering experiments.

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