[gmx-users] problem going from cut-off to pme
Mark.Abraham at anu.edu.au
Wed Mar 8 07:14:26 CET 2006
> I have a strange problem with a 100 molecule system where I used cut-
> off electrostatics and I want to use pme from now.
> After md with Coulomb cut-off, I minimised with steep (and the same
> Coulomb cut-off) and it ends OK:
> I take this minimised .gro and I minimise it again but now I change to
> PME electrostatics. It crashes from the beginning with an infinite
> force (not on the atom with the previous maximum force) and the energy
> is huge: 6.56504e+19 instead of -5.0425977e+04 which was the end of the
> previous minimisation. Do you have any explanation? Should I change
> some PME parameters?
This suggests you are doing something grossly wrong. Check your
structures visually, check you're actually feeding in the structure you
think you are, check your .mdp file contains what you think it does.
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