[lammps-users] Polymer Nanocomposite: Volume Rescale

       My system is a polymer nanocomposite. I have built the structure with a low initial density. Now i would like to compress it to make it more denser. The nanotube in the system in an infinite one. All what i want is to compress the polymer and not the nanotube (as the embedded structure itself is the proper structure of the same) in the system. So i defined two groups, nanotube and polyimide and applied volume rescale command only for the polyimide portion. Is this approach of mine ok ? To make things little less complicated i am not compressing the cell in the z direction , the axial direction of the nanotube. Do i also need to use another volume rescale command for nanotube separately to ensure it is not compressed due to the unit cell compression. Or there is any other better way of doing the same. Any input will be appreciated. Thanking in advance.


What you are doing with volume rescale sounds fine.

You could also try using fix npt with the "dilate partial" option
to only rescale the surrounding fluid. See the doc for
the fix npt command for details.