first off, please always reply to the list, e.g. by using "reply-to all", thank.
I just tried "hftn", it does better, now the final Fmax is of order
10^-3, (0.0023240066 below).
My final purpose is to find two adjacent minimums, and run NEB to see
the barrier in between.
Do you think Fmax~10^-3 is good enough for my purpose ?
how should i know?
And, you said "it can be prohibited by symmetry, e.g. when an atom is
jammed between two others.".
Do you mean three atoms in a line, although the middle one has
non-zero net force (direction of force is also in the line) but
further moving will cause it to be too close to the other two so it
just stops there ? Can you please explain more ? I don't get it.
when one atom is "jammed" between two or more others,
than its force is not exactly zero in absolute terms, but any
(finite) move away will create a much larger force. so relatively
speaking the force considered converged. the way out would
be to move "sideways" but there may not be a sufficient
gradient in that direction. this is what i mean by "symmetry",
since this can only happen if the environment is fairly symmetric.
axel.