[gmx-users] Stepsize too small, or no change in energy

Pradip Kumar Biswas p.biswas at csuohio.edu
Tue Jul 18 16:20:45 CEST 2006


What is your 'emstep'  value in your mdp file? Could you try to rerun 
your system with a low emstep; say with emstep = 0.00001
or else?


On Jul 18, 2006, at 1:13 AM, Srivastava, Dhiraj (UMC-Student) wrote:

> Hi all
>       when i am trying to minimize my structure, i am getting 
> following error.
> Stepsize too small, or no change in energy.
> Converged to machine precision,
> but not to the requested precision Fmax < 1000
> Double precision normally gives you higher accuracy.
> writing lowest energy coordinates.
> Back Off! I just backed up prodh_em.trr to ./#prodh_em.trr.2#
> Back Off! I just backed up prodh_wb.pdb to ./#prodh_wb.pdb.4#
> Steepest Descents converged to machine precision in 45 steps,
> but did not reach the requested Fmax < 1000.
> Potential Energy  = -1.8373166e+06
> Maximum force     =  1.5158329e+04 on atom 519
> Norm of force     =  3.1759754e+04
> i have tried the conjugated gradient, constraint none and also 
> included flexible water but still i am getting the same error.
> what should i do to solve this problem?
> Thanks in advance for help.
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Pradip K. Biswas, PhD.
Research Associate, Department of Chemistry;
Cleveland State University, Ohio-44115
Phone: 1-216-875-9723
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