[gmx-users] Free energy perturbation of ligand

[TIASHA ADHIKARY]

Hello,
I am trying to calculate FEP using gromacs. I have used pmx for initial structure and .itp file.
I am getting the following warning

WARNING 1 [file MOL.itp, line 185]:
  Some parameters for bonded interaction involving perturbed atoms are
  specified explicitly in state A, but not B - copying A to B

Even if I ignore this warning, structure is not minimizing.

"Steepest Descents converged to machine precision in 185 steps,
but did not reach the requested Fmax < 100.
Potential Energy  =  1.8540598e+08
Maximum force     =  5.4468039e+04 on atom 6
Norm of force     =  2.0960916e+03"

I am not understanding how to solve this error. I will be highly obliged if anybody help me.

Thanks in advance.

Regards,
Tiasha Adhikary
M.Tech, IIT Guwahati