# Forces have not converged during energy minimization

**URL:** <https://gromacs.bioexcel.eu/t/forces-have-not-converged-during-energy-minimization/12105>\
**Category:** User discussions\
**Tags:** energy-minization\
**Created:** [May 18, 2025, 12:38pm UTC](https://gromacs.bioexcel.eu/t/forces-have-not-converged-during-energy-minimization/12105 "2025-05-18T12:38:52Z")\
**Posts on this page:** 1\
**Page:** 1

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**Author:** ![mannu](https://avatars.discourse-cdn.com/v4/letter/m/54ee81/32.png) [@mannu](https://gromacs.bioexcel.eu/u/mannu)\
**Post date:** [May 18, 2025, 12:38pm UTC](https://gromacs.bioexcel.eu/t/forces-have-not-converged-during-energy-minimization/12105/1 "2025-05-18T12:38:52Z")

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Hi everyone,

Forces does not converge. The bonds also distort in the final frame/ long distance.

GROMACS version: 2024.4  
GROMACS modification: Yes  
Energy minimization has stopped, but the forces have not converged to the  
requested precision Fmax \< 500 (which may not be possible for your system).  
It stopped because the algorithm tried to make a new step whose size was too  
small, or there was no change in the energy since last step. Either way, we  
regard the minimization as converged to within the available machine  
precision, given your starting configuration and EM parameters.

Double precision normally gives you higher accuracy, but this is often not  
needed for preparing to run molecular dynamics.  
You might need to increase your constraint accuracy, or turn  
off constraints altogether (set constraints = none in mdp file)

writing lowest energy coordinates.

Back Off! I just backed up em.gro to ./#em.gro.1#

Steepest Descents converged to machine precision in 2062 steps,  
but did not reach the requested Fmax \< 500.  
Potential Energy = -5.0807432e+07  
Maximum force = 1.5580516e+04 on atom 169932  
Norm of force = 2.1943692e+01

mdp file:

integrator = steep  
emtol = 500.0  
nsteps = 100000  
nstlist = 10  
cutoff-scheme = Verlet  
rlist = 1.2  
vdwtype = Cut-off  
vdw-modifier = Force-switch  
rvdw\_switch = 1.0  
rvdw = 1.2  
coulombtype = PME  
rcoulomb = 1.2  
;  
constraints = h-bonds  
constraint\_algorithm = LINCS

Can I remove the constraints to avoid this error?

Thanking you  
Manisha