[gmx-users] stepsize too small

burkhard rammner rammner at scimotion.de
Mon Aug 13 20:08:40 CEST 2007


This is the first time I`m using gromacs.
That`s why I`m having a beginners`question.
I tried to do an energy minimization, but after 45 steps this message 
and I know that the following lines have led to questions before:

"Stepsize too small (9.09769e-007 nm)Converged to machine precision,
but not to the requested precision (1000)"

I`m using single precision windows compiled gromacs. I know, I have
to change whatever parameter, but so far I didn`t succeed.

This is the mdp file:

integrator        = steep           
emtol              = 1000           
emstep           = 0.01
nsteps            = 200           
nstenergy       = 10               
nstxtcout        = 10               
xtc_grps        = Protein           
energygrps     = Protein           
nstlist             = 5           
ns_type         = simple       
rlist               = 1.0               
coulombtype    = cut-off           
rcoulomb      = 1.0               
rvdw            = 1.0               
constraints    = none           
pbc              = no       

So, what`s wrong here?
What do I have to change?

Many thanks for help!



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