[gmx-users] Problem in energy minimization

[Jin J.C]

Dear all,
I am trying to set a coarse-grained MD for the membrane protein.
After solvating, I met an error when running a short energy minimization (
10 steps) before adding ions.

Steepest Descents:
Tolerance (Fmax)   =  1.00000e+01
Number of steps    =           10
Step=   10, Dmax= 2.0e-05 nm, Epot=  2.76192e+20 Fmax=         inf, atom=
8872
Reached the maximum number of steps before reaching Fmax < 10 writing
lowest energy coordinates.
Steepest Descents did not converge to Fmax < 10 in 11 steps.
Potential Energy  =  2.7619190e+20
Maximum force    =           inf on atom 8872
Norm of force       =            inf

The reason is because of Maximum force is equal to infinity. Therefore I
can not proceed further. Atom 8872 is water atom. Even when I delete this
atom, the error occurs again with another water molecules, and goes on.

Can someone help me figure out? and explain to me what happen?  Is this
because of overlapping problem?

Thank you so much
Jin