Editing Radial Distribution Function

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                                                         | RADIAL DISTRIBUTION FUNCTION | ''(by Luca)''
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You can find the definition of the Radial Distribution Function (RDF) in the following:
 
http://rings-code.sourceforge.net/index.php?option=com_content&view=article&id=50:rdf&catid=36:phy-chi&Itemid=58



'''Name''': ''x.RDF''

'''Launching''': ''x.RDF > output'' (in ''output'' some details of the calculation are reported)

'''Input file''': ''geom.dat'', ''param.dat''

'''Output file''': ''Global.dat'', ''fort.X'' (X = 1, 2, ..., N; see below)

'''Used subprograms''': ''none''


* '''General Description'''

''x.RDF'' takes a system described in ''geom.dat'' and creates other 26 replica of the system adding or subtracting the lattice vectors.
The initial system is at the centre of this 3x3x3 supersystem.
It then computes the distances between the atoms in the initial system and the atoms in all the 26 outer cells, and inside the initial cell as well.
It then computes the RDF and write it in ''fort.X'' (X = 1, N).


* Description of the '''Input files'''

In ''geom.dat'' there are the coordinates and label of all the atoms of my system '''in XYZ'''.
Moreover, all atoms have to be written "in the VASP way", i.e. first all the atoms of type A, then all the atoms of type B and so on.
An example of ''geom.dat'' for a box of 96 water molecules is reported here: [[Image:ex_geomRDF.tgz]]

In ''param.dat'', many different parameters, specifying the cell size and what kind of RDF you want, are specified. Here I attach an example:
[[Image:ex_paramRDF.tgz]] and in that page you can find all the explanation you need.


* Description of the '''Output files'''

In ''Global.dat'' you will find the positions of the atoms of your initial system, and their projections in all the other 26 contiguous cells.

In ''fort.X'' (X = 1, 2... N) you will find your RDF for the category X; please, see the link  [[Image:ex_paramRDF.tgz]] for more details about categories. Hence, if you specified 4 categories, you will have 4 output files (''fort.1'', ''fort.2'', ''fort.3'' and ''fort.4''), one for each category.


* '''INSTALLATION STEPS'''


1) First of all, download the program:

-       [[Image:RDF.tgz]]

and the example for the ''param.dat'' file: [[Image:ex_paramRDF.tgz]].

Uncompress them and compile the program: ''f77 RDF.f -o x.RDF''. Place it in a directory of your choice (for simplicity, named directory A).


2) Copy your geometry in the file ''geom.dat'' (as I said, it has to be an XYZ file with all the atoms ordered by type).

3) Change the parameters in the ''param.dat'' file as you wish.
 
4) Now you can run the program typing:  ''x.RDF > output''

5) The files ''fort.X'' are ready to be plotted with ''gnuplot''.