Well the question is how this could happen? I mean why the a-b RDF or g® is just a function of \sigma in leonnard johnes potential?
and why system reports that, in which it cannot happen spatially?
Thanks Hamid
I’d say you are asking the wrong questions and making assumptions that are not justified.
The code in compute rdf and in the lj/cut pair style as well as other basic functionality has been tried and tested over many years and validated to work correctly time and again. So if you are using those features correctly, you are getting answers that represent the physical reality of your input deck.
Whether this is the physical reality that you are expecting, I cannot say. that is for you to figure out.
If you can produce a simple and easy (and quick) to run input deck, where you can prove that LAMMPS is not working correctly, then we can discuss again. But based on the experience from previous years and having tested and debugged features like compute rdf and other parts of LAMMPS repeatedly, i am quite confident, that we are more likely to find a discrepancy in your input to what you expect it does.
My recommendation is that you take a step back, and build a simpler input deck and double check everything and then gradually transform that input deck into your desired system and watch where things get out of whack.
Axel.