Dear Mr. Nursya
The difference between RDF(Radial Distribution Function) and PDF (Proximal Distribution Function)
is explained here
https://www.r-ccs.riken.jp/labs/cbrt/samples/rdf_analysis/
RDF calculates the number density of solvents as a function of the distance from a target atom.
PDF calculates the number density of solvents as a function of the distance to the closest atom in the
target molecule.
PDF is useful to analyze the solvent density distribution around the macromolecules, such as proteins.
Best regards,
Isseki