Dear Dr. Axel Kohlmeyer and LAMMPS Users,
Hello All. I am simulating an MD run that relaxes a system of equilibrated polymer chains under constant temperature and the pressure and the volume is allowed to fluctuate.
The nonconnected beads in a chain are governed by repulsive LJ potential and connecting bonds are governed by the FENE potential as displayed in the following:
pair_style lj/cut 1.122462
special_bonds lj 0.0 1.0 1.0
pair_coeff * * 1.0 1.0 1.122462
bond_coeff * 30.0 1.5 1.0 1.0
pair_modify shift yes
What is the difference between the following two cases that does stress relaxation of the polymer chains
fix 1 all langevin 1.0 1.0 2.0 542305
fix 2 all press/berendsen iso 0.0 0.0 10.0
fix 3 all nve
fix 1 all npt temp 1.0 1.0 2.0 iso 0.0 0.0 10.0
I ran both of these MD simulations without any error and I plotted the volume of the simulation box with respect to time. I see that the Case 2 resulted in a slightly higher volume at the end of the run (meaning that the relaxation inflated the system) but overall I do not see any significant difference between these two cases.
I would greatly appreciate if anyone could provide me with any comments. Thank you so much for your time.