Hi,

I have 1000 polymers made up of 200 lennard jones atoms with fene bond

connections. I want to calculate the diffusion coefficient of the

polymers. I can use compute com or compute msd. Compute msd does not

give good statistics as it does not use the values of previous

timesteps so the best way that I see to go about this is to dump the

center of mass coordinates of each polymer and calculate the mean

squared displacement using the com's. However, I am limited to 32

groups which I can use in "compute com". I could dump the coordinates

of each atom and post process to get the polymer center of mass

coordinates but this would mean I will be dumping 200 numbers more in

comparison to just dumping the center of mass of the polymer.

Maybe there are new features in LAMMPS that I don't know to get around

my problem of how to efficiently obtain the center of mass of more

than 32 polymers. Any help or suggestions is very much welcomed.

Jan-Michael