I am running NEB in LAMMPS using an etol of 0 and an ftol of 2.5e-5. Sometimes I get the following stopping criterion?
Stopping criterion = max iterations with v.f negative
What does it mean and are there any suggestion to avoid it?
If nothing else helps and nobody answers, the solution is to look at the source code and see if there is any hint in the comments.
The error message you quoted corresponds to the constant MAXVDOTF.
This is only used in one place: in the file min_fire.cpp:
// stopping criterion while stuck in a local bassin of the PES
if (max_vdotf_negatif > 0 && vdotf_negatif > max_vdotf_negatif)
I suggest you take it from there and check out the code leading up to this and possible compile time constants or options to min_modify if there are ways to avoid this, or whether this is rather an acceptable result for the kind of system you have.
If you really want to, you can ignore this stopping criterion by setting vdfmax=0
“An additional stopping criteria vdfmax is used by fire in order to avoid unnecessary looping when it is reasonable to think the system will not be relaxed further. Note that in this case the system will NOT have reached your minimization criteria. This could happen when the system comes to be stuck in a local basin of the phase space. vdfmax is the maximum number of consecutive iterations with P(t) < 0.”