Distribution Function and Angular Deformations of a Model Related to Vitreous Ice and Liquid Water

1974 ◽  
Vol 52 (10) ◽  
pp. 1945-1953 ◽  
Author(s):  
G. S. Kell
Keyword(s):  
Distribution Function ◽  
Liquid Water ◽  
Nearest Neighbors ◽  
Minimum Density ◽  
Hexagonal Ice ◽  
Oxygen Oxygen ◽  
Small Deformations ◽  
Tetrahedral System ◽  
Measured Density

A random tetrahedral model, without bonding defects and in which the distance between nearest neighbors is constant, has been constructed to study the effect of angular variations from tetrahedral, and the observations have been interpreted in terms of vitreous ice and liquid water. The model was constructed to have relatively small deformations from tetrahedral, and the oxygen–oxygen–oxygen angles vary from 90 to 132°, with an interquartile width of 12°. The measured density is intermediate between that of hexagonal ice and liquid water and, because of the small angular deformations, provides an estimate both of the density of vitreous water and of the minimum density possible for a random tetrahedral system.

scholarly journals PDF Analysis on a Laboratory System: Adapting the Experiment to the Material

2014 ◽  
Vol 70 (a1) ◽  
pp. C870-C870
Author(s):  
Céleste Reiss ◽  
Milen Gateshki ◽  
Marco Sommariva
Keyword(s):  
Distribution Function ◽  
Pair Distribution Function ◽  
Amorphous Materials ◽  
Nearest Neighbors ◽  
High Energy ◽  
Experimental Point ◽  
Laboratory System ◽  
Crystalline Materials ◽  
X Ray ◽  
Pdf Analysis

The increased interest in recent years regarding the properties and applications of nanomaterials has also created the need to characterize the structures of these materials. However, due to the lack of long-range atomic ordering, the structures of nanostructured and amorphous materials are not accessible by conventional diffraction methods used to study crystalline materials. One of the most promising techniques to study nanostructures using X-ray diffraction is by using the total scattering (Bragg peaks and diffuse scattering) from the samples and the pair distribution function (PDF) analysis. The pair distribution function provides the probability of finding atoms separated by a certain distance. This function is not direction-dependent; it only looks at the absolute value of the distance between the nearest neighbors, the next nearest neighbors and so on. The method can therefore also be used to analyze non-crystalline materials. From experimental point of view a typical PDF analysis requires the use of intense high-energy X-ray radiation (E ≥ 20 KeV) and a wide 2θ range. After the initial feasibility studies regarding the use of standard laboratory diffraction equipment for PDF analysis [1-3] this application has been further developed to achieve improved data quality and to extend the range of materials, environmental conditions and geometrical configurations that can be used for PDF experiments. Studies performed on different nanocrystalline and amorphous materials of scientific and technological interest, including organic substances, oxides, metallic alloys, etc. have demonstrated that PDF analysis with a laboratory diffractometer can be a valuable tool for structural characterization of nanomaterials. This contribution presents several examples of laboratory PDF studies, in which the experimental conditions have been successfully adapted to match the specific requirements of materials under investigation.

scholarly journals The temperature dependence of intermediate range oxygen-oxygen correlations in liquid water

2016 ◽  
Vol 145 (8) ◽  
pp. 084503 ◽  
Author(s):  
Daniel Schlesinger ◽  
K. Thor Wikfeldt ◽  
Lawrie B. Skinner ◽  
Chris J. Benmore ◽  
Anders Nilsson ◽  
...  
Keyword(s):  
Temperature Dependence ◽  
Liquid Water ◽  
Intermediate Range ◽  
Oxygen Oxygen

scholarly journals Correlation magnetodynamics equations taking into account the uniaxial quadratic correction in the approximation of the one-particle distribution function

2021 ◽  
pp. 1-16
Author(s):  
Anton Valerievich Ivanov
Keyword(s):  
Distribution Function ◽  
Particle Distribution ◽  
Nearest Neighbors ◽  
Particle Distribution Function ◽  
Phase Transition Region ◽  
Simulation Results ◽  
The One ◽  
Bogolyubov Chain ◽  
New System ◽  
Good Agreement

The system of equations for correlation magnetodynamics (CMD) is based on the Bogolyubov chain and approximation of the two-particle distribution function taking into account the correlations between the nearest neighbors. CMD provides good agreement with atom-for-atom simulation results (which are considered ab initio), but there is some discrepancy in the phase transition region. To solve this problem, a new system of CMD equations is constructed, which takes into account the quadratic correction in the approximation of the one-particle distribution function. The system can be simplified in a uniaxial case.

States of a dispersed nonwetting liquid in a disordered nanoporous medium

2015 ◽  
Vol 29 (15) ◽  
pp. 1550097 ◽  
Author(s):  
Vladimir D. Borman ◽  
Anton A. Belogorlov ◽  
Alexey M. Grekhov ◽  
Vladimir N. Tronin
Keyword(s):  
Porous Media ◽  
Distribution Function ◽  
Liquid Water ◽  
Water System ◽  
Percolation Cluster ◽  
Water Systems ◽  
Size Distribution Function ◽  
Nonwetting Liquid ◽  
Disordered Porous Media ◽  
Degree Of Filling

Three different states of a dispersed nonwetting liquid (water) in the Fluka 100 C8 and Fluka 100 C18 disordered porous media, as well as transitions between these states under variation of the temperature and the degree of filling, have been revealed. It has been shown that the appearance of such states is due to the broadening of the pore size distribution function f(R), fluctuations of configurations of neighbors in the system of pores and fluctuations in the configuration of a pore and its environment consisting of filled and empty pores in the percolation cluster. These states and transitions are caused by the competition between the effective repulsion of the nonwetting liquid from the wall of the pore, which is responsible for the "extrusion" of the liquid from the pore, and the effective collective "multiparticle" attraction of the liquid cluster in the pore to clusters in the neighboring connected pores. The observed difference in the behavior of the Fluka 100 C8/water and Fluka 100 C18/water systems and the previously studied Libersorb-23 (L23)/water system indicates a significant dependence of the state of these systems on the type of disorder in them.

Benchmark oxygen-oxygen pair-distribution function of ambient water from x-ray diffraction measurements with a wide Q-range

2013 ◽  
Vol 138 (7) ◽  
pp. 074506 ◽  
Author(s):  
Lawrie B. Skinner ◽  
Congcong Huang ◽  
Daniel Schlesinger ◽  
Lars G. M. Pettersson ◽  
Anders Nilsson ◽  
...  
Keyword(s):  
Distribution Function ◽  
Pair Distribution Function ◽  
Ambient Water ◽  
X Ray Diffraction ◽  
X Ray ◽  
Oxygen Oxygen
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