I am trying to create polymers using atom style hybrid molecular dipole. I am getting the warning messages as
“WARNING: FENE bond too long: 283016 1883 1884 1.4230823275030267 (src/MOLECULE/bond_fene.cpp:89)”
How to rectify this error?
Please clarify this
Thanks in advance
There is no common, always applicable answer for this. When a bond stretches too much, this can mean that you have bad force field parameters, or a high potential energy initial geometry, that you have bad simulation settings, a bad bond topology and so on.
But this should not happen for ideal conditions. As i am using bond coefficient 30, this message is showing and for higher bond coefficient it is not observed. for example for 240 it is not observed. But we cannot use higher value as the polymer should be flexible. How to set the force fields properly?
Well – yes – “FENE” stands for finite extensible nonlinear elastic bonds. The bond energy (and thus force) diverges at a finite bond length (unlike a harmonic bond, which always has finite energy and force whether physically valid or not), reflecting that polymer bonds are not infinitely extensible in real life either.
Your polymer’s bead distances should not be exceeding that finite limit. If they are, then either your force field or your timestep is wrong at minimum (or you may have an initial clash and subsequent blowout).
Thanks for your reply sir,
Is there any way to fix this error?