[gmx-users] (no subject)

[Sadaf Rani]

Dear Gromacs users
I am running a free energy calculation of the protein-ligand complex.
During the energy minimization process, I am getting many jumps in steps as
below:-

Step           Time
          10500    10500.00000

   Energies (kJ/mol)
           Bond Restraint Pot.          Angle    Proper Dih.  Improper Dih.
    1.20860e+03    1.65864e+00    4.67218e+03    1.83350e+04    1.87873e+02
          LJ-14     Coulomb-14        LJ (SR)  Disper. corr.   Coulomb (SR)
    6.81295e+03    7.12692e+04    3.37954e+05   -6.56537e+03   -2.70668e+06
   Coul. recip.    Angle Rest.     Dih. Rest.      Potential Pres. DC (bar)
    4.78029e+03    5.32468e+00    3.32764e+00   -2.26802e+06    0.00000e+00
 Pressure (bar)    dVremain/dl       dEkin/dl      dVcoul/dl       dVvdw/dl
   -2.69428e+04    0.00000e+00    0.00000e+00    2.78529e+03   -1.65404e+02
 dVrestraint/dl   Constr. rmsd
    0.00000e+00    2.71623e-06

           Step           Time
          10501    10501.00000

           Step           Time
          10502    10502.00000

           Step           Time
          10503    10503.00000

           Step           Time
          10504    10504.00000

           Step           Time
          10505    10505.00000

           Step           Time
          10506    10506.00000

           Step           Time
          10507    10507.00000

           Step           Time
          10508    10508.00000

           Step           Time
          10509    10509.00000

           Step           Time
          10510    10510.00000

           Step           Time
          10511    10511.00000


Energy minimization has stopped, but the forces have not converged to the
requested precision Fmax < 10 (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)

Steepest Descents converged to machine precision in 10512 steps,
but did not reach the requested Fmax < 10.
Potential Energy  = -2.2680185e+06
Maximum force     =  6.3521606e+02 on atom 4653
Norm of force     =  3.6713926e+00

Should I use double precision for energy minimization?
I need your suggestions,
 please.

Thanks

Sadaf Rani