[gmx-users] Positive potential energy during Energy minimization step

[neha bharti]

I am trying to perform MD for protein ligand protein complex in popc lipid
with charmm36 force field and also follow Justin A. Lemkul tutorial.

After Adding Ion

genion -s ions.tpr -o pro_POPC_sol_ions.gro -p topol.top -pname NA -np 1
-nname CL

I preform energy minimization step. In energy minimization step I am
getting possitive potential enargy:

Steepest Descents converged to machine precision in 18 steps,
but did not reach the requested Fmax < 1000.
Potential Energy  =  6.1499341e+17
Maximum force     =            inf on atom 3300
Norm of force     =  5.4206209e+18


its mention in the tutorial verify that the values of Epot and Fmax are
reasonable before continuing

I am trying alot but not able to fix the issue.

Its mention in tutorial but I am not able to find the exactly what to do.

please help.

With Regards
Neha bharty