A python script to generate RDF (radial distribution function or pair correlation function) from particle coordinates in PDB files:
Here is a parallel version of the above script: rdf_from_pdb_parallel_box_cgcg.py
It "distributes" the PDB files among all the available CPU's. It uses Python's Pool, so you do not need any aditional libraries or modules.
You have to set the box size, and possibly some other things. Modify to your needs.
To run it, make the script executable, then run it with the PDB directory as the argument: