[gmx-users] "Stepsize too small" - please help to understand this!!!

Semen Esilevsky yesint4 at yahoo.com
Fri Jun 25 15:35:46 CEST 2004

Dear all,
I'm triyng to run an energy minimization of the lipid
bilayer, but I constantly have the same problem:

Stepsize too small (8.60519e-07 nm)Converged to
machine precision,
but not to the requested precision (200)

I know that this question was already discussed, but I
can't find a comprehencive answer in the archive.

As far as I understand this message means that the sd
optimizer can't make the force smaller and thus the
step is constantly decreased until it reaches zero. Is
it so?
If this happence, is it possible to look at the 
*gradients* (not energies!) to see how well the
structure is optimized? I didn't find any record of
the hradients during em...

Thank you in advance for reply!


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