I was trying to reproduce the results of Kremer and
Grest in which they obtain the diffusion constant of a
neat polymer melt with repulsive interactions. Their
system is comprised of 75 polymer chains with 80
monomer beads in each chain. The parameter values are
epsilon = sigma = mass = 1.0, temp = 1.0*epsilon and
density = 0.85 (all LJ units).
They found the diffusion constant to be equal to
4.55E-04 (which in the order of N**-2, where N is the
number of bonds in each chain).
I tried to take the same system and redo it using
LAMMPS to obtain the diffusion constant equal to
2.89E-03. To double check my results, I also used the
fix msd command in LAMMPS, which also gave me the same
I am attaching my input file to this email. It would
be great if someone (who has done this before) could
help me out and give any suggestions.
in.prod (1.29 KB)