[lammps-users] Bad FENE bond!


I generate a number of atoms using lattice fcc with the maximum number dencity for the region block , but always I get this error of bad FENE bond and two atoms in a FENE bond have become so far apart that the bond cannot be computed! I do not know what else I can do! please advice me what I can do to solve this error!



That is a symptom of somehting wrong with your model. How far apart
are they? Why did they move far apart? Could be many reasons,
all of them the fault of your model. Bad initial state, too big a timestep,


Steve, they are about 3-4 LJ units! I simply generate the atoms with lattice fcc command! then I dump them in a file and use the file as data file in my model. Even before using these data in my model, I can see the largest distances of 3-4 and LAMMPSexactly picks and report them in error message. then again I increased the number density but I can see in my log file that the volume also is increased, therefore, I supposed the increaseing number density is not soloution!

With standard coeffs, the FENE potential cannot extend beyond about 1.5 sigma
before the formula blows up (goes to infinity), and the equilibrium bond length
is about 0.97 sigma. Soyou cannot initially put
bonded atoms 3-4 sigma apart. Please study/plot the formula on the doc
page with the coeffs you have set and verify that you have a reasonable model.