[lammps-users] Higher Dimensional Distribution Functions (Beyond RDF)
James Mansell <jmmansel@...1442...>
Fri, 11 May 2018 13:17:19 -0400
Hello LAMMPS users,
I would like to calculate the two-particle (pair) distribution function in small systems with external potentials having continuous "infinitely long" cylindrical symmetry. [Forgive my abuse of terminology.] Due to the external potential, RDF is no longer a sufficient descriptor. I need four dimensions to describe this distribution.
After searching the documentation and mailing list archives, I have not found any discussions of such a requirement, but I figure it is worth a shot to ask the following:
1. Does LAMMPS have any standard compute or other capability that might be helpful for doing this that I have overlooked?
2. Has anyone out there done something like this, or know of anyone who has done it, that could be helpful?
3. Is this a somewhat reasonable thing to try to implement (in LAMMPS)? I am considering writing a compute, which I have not done before. I would rather know in advance if more experienced users think this is a bad idea (not that I would not try it anyway).
Incidentally, my systems are quite small and simple ( < 2,500 LJ particles, < 2,000 nm^-3), and by taking advantage of symmetries and other information, I believe a suitable "mesh" could be produced with fewer than 1E9 bins, perhaps significantly fewer. So, it seems like the curse of dimensionality should be manageable IF I am careful.
I guess I could also consider a spatial decomposition other than discrete bins. Or some other method entirely?
Any help is much appreciated.