Dear Dr. Axel Kohlmeyer and LAMMPS Users,
Hello All. I am currently simulating 100 polymer chains that crosslink between the same Type 3 beads and between the same Type 4 beads using the Kremer-Grest bead (coarse-grained) spring model. The non-connected bonds are governed by the LJ potential (cutoff of 2.5 using LJ units) whereas the connecting bonds and including the newly formed crosslinked bonds are governed by the FENE potential. (K = 30 R = 1.5)
I have attached my input script which reads the data file that contains the coordinates of equilibrated 100 polymer chains. (The initial configuration of 100 separate chains is well-equilibrated) When I use only 8 processors to run the input script, it runs fine free of any warnings or errors.
However, when I use 27 processors without changing my input script and the data file, I obtain a FENE bond too long error after 300 timesteps.
(ERROR on proc 55: Bad FENE bond)
I inserted the minimize command:
minimize 1e-25 1e-25 500000 1000000
Inserting this minimize command allowed me to run the simulation for a while but the simulation terminated after 2081 timesteps with
(ERROR on proc 55: Bond atoms 16222 16223 missing on proc 55 at step 2081)
I understand that both of these errors are due to bad dynamics or bad force fields.
My force fields are standard using the typical Kremer-Grest bead spring parameters, and moreover, the simulation works perfectly fine and the crosslinking process occurs when using only 8 processors.
However, without changing anything except for using 64 cores, I obtain the above errors.
After searching through the mailing list, my pairwise cutoff distance + skin distance greatly exceeds the maximum extension of the FENE bonds. Moreover, I frequently build my neighbor list since fix bond_create will require the neighbor list to be updated.
I am aware that using less number of processors for parallel simulations is preferable. Nevertheless, I would greatly appreciate for any advice on how I can resolve this issue when using larger number of processors. Thank you very much for your time.
Polymerize_100chains.in (1.81 KB)