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Physics and chemistry
This part of the documentation presents with details the physical and chemical properties that can be computed using the R.I.N.G.S. code

Local atomic coordination properties

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Several properties related to the atomic bonds and angles between them can be computed using the R.I.N.G.S. code
In the R.I.N.G.S. code the existence or the absence of a bond between two atoms i of species α and j of species β is determined by the analysis of the partial gαβ(r) and total g(r) radial distribution functions.
Precisely the program will consider that a bond exists if the interatomic distance Dij is smaller than both the cutoff given to desribe the maximum distance for first neighbor atoms between the species α and β, Rcutαβ (often the first minimum of the partial radial distribution function gαβ(r) ), and the first minimum of the total radial distribution function, Rcuttot.

Last Updated on Sunday, 15 November 2009 18:54 Read more...
 

Ring statistics

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The analysis of topological networks (liquid, crystalline or amorphous systems) is often based on the part of the structural information which can be represented in the graph theory using nodes for the atoms and links for the bonds. The absence or the existence of a link between two nodes is determined by the analysis of the total and partial radial distribution functions of the system.

In such a network a series of nodes and links connected sequentially without overlap is called a path. Following this definition a ring is therefore simply a closed path.

If we study thoroughly a specific node of this network we see that this node can be involved in numerous rings.
Each of these rings is characterized by its size and can be classified based upon the relations between the nodes and the links which constitute it.

Last Updated on Wednesday, 10 November 2010 11:20 Read more...
 

Bond defects in ring statistics

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Ring statistics have been developed mainly to study the connectivity of amorphous materials.
However, the wide variety of sequences and structural defects that may be encountered in these materials make this type of analysis particularly challenging.
Some scenarios should therefore be reviewed, to lay the groundwork to look for rings in these compounds. In particular we need to evaluate the influence of different bond defects in the amorphous network.
However, in each case both the impact on the connectivity, and the impact on the physical properties which can be deduced from the analysis, have to be studied.
Furthermore it is necessary to determine if the influence of the bond defects depends on the criteria used to define a ring.

Last Updated on Thursday, 09 December 2010 07:34 Read more...
 

Further in ring statistics

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For now it is impossible to compare the results of ring statistics to experimental data. Therefore we have decided to improve the description of the both the network and the material on the basis proposed by the ring statistics.
The main goal is to allow to link this analysis method to other physical properties of the material that can be measured experimentally.

The following article illustrates features implemented in the R.I.N.G.S. code in order to improve the results of the ring statistics.

Last Updated on Thursday, 09 December 2010 06:01 Read more...
 

Simulation of neutrons and X-rays scattering

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An alternative way to analyze the results of molecular dynamics simulations is to compute the static neutrons and X-rays structure factors S(q). 
S(q) allows to study the organization of the particles in the material and can be directly compared to neutrons and X-rays scattering experiments.

Thereafter you will find the theoretical elements that will help you to understand theses techniques, and to obtain an overview of the formalisms implemented in the R.I.N.G.S. code.

 

Last Updated on Monday, 23 June 2014 05:01 Read more...
 
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