# The force on at least one atom is not finite. This usually means atoms are overlapping

**URL:** <https://gromacs.bioexcel.eu/t/the-force-on-at-least-one-atom-is-not-finite-this-usually-means-atoms-are-overlapping/10927>\
**Category:** User discussions\
**Created:** [January 1, 2025, 12:14pm UTC](https://gromacs.bioexcel.eu/t/the-force-on-at-least-one-atom-is-not-finite-this-usually-means-atoms-are-overlapping/10927 "2025-01-01T12:14:34Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![Hridhya\_04](https://avatars.discourse-cdn.com/v4/letter/h/9f8e36/32.png) [@Hridhya\_04](https://gromacs.bioexcel.eu/u/Hridhya_04)\
**Post date:** [January 1, 2025, 12:14pm UTC](https://gromacs.bioexcel.eu/t/the-force-on-at-least-one-atom-is-not-finite-this-usually-means-atoms-are-overlapping/10927/1 "2025-01-01T12:14:34Z")

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GROMACS version: 2024.2  
GROMACS modification: Yes/No  
Here post your question

 ![image](https://europe1.discourse-cdn.com/flex017/uploads/bioexcel1/original/2X/5/5f454cecd55465a1b059377d3bdd00f87a67a7ca.png)

Command line:  
gmx\_mpi mdrun -v -deffnm em

Back Off! I just backed up em.log to ./#em.log.2#  
Reading file em.tpr, VERSION 2024.1 (single precision)  
Update groups can not be used for this system because atoms that are (in)directly constrained together are interdispersed with other atoms

Using 1 MPI process  
Using 32 OpenMP threads

Back Off! I just backed up em.trr to ./#em.trr.2#

Back Off! I just backed up em.edr to ./#em.edr.2#

Steepest Descents:  
Tolerance (Fmax) = 1.00000e+03  
Number of steps = 5000  
Step= 0, Dmax= 1.0e-02 nm, Epot= 2.33906e+18 Fmax= inf, atom= 252478  
Step= 1, Dmax= 1.0e-02 nm, Epot= 2.33887e+18 Fmax= inf, atom= 252478  
Step= 2, Dmax= 1.2e-02 nm, Epot= 2.33887e+18 Fmax= inf, atom= 252478  
Step= 3, Dmax= 1.4e-02 nm, Epot= 2.33885e+18 Fmax= inf, atom= 252478  
Step= 4, Dmax= 1.7e-02 nm, Epot= 2.33885e+18 Fmax= inf, atom= 252478  
Step= 19, Dmax= 1.3e-06 nm, Epot= 2.33885e+18 Fmax= inf, atom= 252478  
Energy minimization has stopped because the force on at least one atom is not  
finite. This usually means atoms are overlapping. Modify the input  
coordinates to remove atom overlap or use soft-core potentials with the free  
energy code to avoid infinite forces.  
You could also be lucky that switching to double precision is sufficient to  
obtain finite forces.

writing lowest energy coordinates.

Back Off! I just backed up em.gro to ./#em.gro.2#

Steepest Descents converged to machine precision in 20 steps,  
but did not reach the requested Fmax \< 1000.  
Potential Energy = 2.3388481e+18  
Maximum force = inf on atom 252478  
Norm of force = inf

The protein is a pentamer with 2 ligands and cations(present in each monomer).  
The GROMACS input file was prepared using charmm gui.  
The size of the monomer : 42kDa

How can i resolve this error?

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**Author:** ![askforarun](https://avatars.discourse-cdn.com/v4/letter/a/c5a1d2/32.png) [@askforarun](https://gromacs.bioexcel.eu/u/askforarun)\
**Post date:** [January 2, 2025, 11:10pm UTC](https://gromacs.bioexcel.eu/t/the-force-on-at-least-one-atom-is-not-finite-this-usually-means-atoms-are-overlapping/10927/2 "2025-01-02T23:10:01Z")

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difficult to diagnose unless the configurations files are provided. Have you tried visualising the atom in vmd and its nearest neighbours ?