[gmx-users] minimization

[Justin A. Lemkul]

mustafa bilsel wrote:
> Hi all,
> At the end of the minimisation I obtained potential energy value 
> approximately -40,000 and I see the following warning
> Stepsize too small, or no change in energy.Converged to machine 
> precision, but not to the requested precision Fmax < 10
> 

Please see the following:

http://www.gromacs.org/Documentation/Errors#Stepsize_too_small.2c_or_no_change_in_energy._Converged_to_machine_precision.2c_but_not_to_the_requested_precision

> As far as I know for succesful minimisation potential energy must be 
> between -100,000 and -1,000,000.

Potential energy is dependent upon system size and the nature of the 
interactions therein.  You should not presuppose a specific value or range thereof.

-Justin

> My em.mdp file as follows
> 
> integrator= steep
> emstep=0.1
> nsteps=10000000
> nstlist=10
> rlist=1.0
> coulombtype=pme
> rcoulomb=1.0
> vdw-type=cut-off
> rvdw=1.0
> nstenergy=10
> 
> My minimisation stops at approximately 19,000 th step.
> Is my minimisation acceptable?If no, how can I correct it?
> 
> best wishes
> Mustafa
> 

-- 
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Justin A. Lemkul
Ph.D. Candidate
ICTAS Doctoral Scholar
MILES-IGERT Trainee
Department of Biochemistry
Virginia Tech
Blacksburg, VA
jalemkul[at]vt.edu | (540) 231-9080
http://www.bevanlab.biochem.vt.edu/Pages/Personal/justin

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