Hi,

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

answer (2.89E-03).

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.

Thanks

VEnkat

in.prod (1.29 KB)