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## Radial distribution functions: rdf.f

This utility compute radial distribution functions between specified atom pairs.

Compilation:

`f77 -O3 -o rdf rdf.f tranal_base.f`

The input into `rdf` utility consists of a NAMELIST section `RDFIN` and subsequent lines defining sites for RDF calculation. The NAMELIST section

     $RDFIN
     parameter=value(s),
     ...
     $END

contains the following parameters

- `FOUTRDF = <filename>`

  The name of the output file

- `NRDF = <int.value>`

  number of RDFs to compute.

- `RDFCUT = <value>`

  Cut-off distance for intermolecular RDF

- `NA = <int.value>`

  Resolution of intermolecular RDF (number of bins within the interval `[0,RDFCUT]`

-     RMI = <value>
      RMAX = <value>

  Boundaries for intramolecular RDFs

- `NAI = <int.value>`

  Resolution of intramolecular RDF (number of bins within the interval `[RMI,RMAX]`

Then a number of lines follows defining the sites for RDFs. In this section all the lines beginning with ``#'' are considered as commentaries. The rules to specify RDFs are the same as in MDynaMix program.

Each (of `NRDF`) RDFs is specified by a single or by several pairs of sites. If RDF is specified by a single pair of sites, two number defining these sites are written in the input. If an RDF needs to be specified by several pair of sites (in order to average them), it is written in the following way:

    &<num of pairs>
    <n1-1>  <n2-1>
    <n1-2>  <n2-2>
    ...

    (<num of pairs> times)

RDFs between sites `<n1-1> <n2-1>` ... are averaged and counted as a single RDF. For example, for water there exists 3 RDFs (`NRDF=3`) and the list of sites may look like (assuming O as a first atom and hydrogens as 2 and 3):

    1  1
    &2
    1  2
    1  2
    &3
    2  2
    2  3
    3  3

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