Hello everyone!
I’m very thankful to who answer my question
Kremer-Grest(KG) model is a successful bead-spring model in polymer physics(JCP,1990,92,5057)
In 2005, they present Primitive Path Analysis(PPA) method to get the entanglement length in KG model(Polym. Phys., 2005,43,917)
Specifically, the intrachain excluded-volume interactions are disabled, whereas the interchain excluded-volumeis retained
Excluded-volume interactions in KG model is LJ potentials
However, in the lammps, bond/FENE comand contains the LJ potentials between two bonded atoms
This partial potential in bond/FENE comand should be disabled
I didn’t find a command could do this, including special_bond command
I find a way is that:
In the src/bond_fene.cpp, I could comment on these code:
// force from LJ term
if (rsq < TWO_1_3sigma[type]sigma[type]) {
sr2 = sigma[type]sigma[type]/rsq;
sr6 = sr2sr2sr2;
fbond += 48.0epsilon[type]sr6(sr6-0.5)/rsq;
}
So, LJ poteneial is none(Energy is not important in PPA)
My question is :
1)Is the method Ok?(I’m not good at C++)
2)Can we do this by some commad in scrpit?
Best wishes,
Yongjin Ruan