[gmx-users] mdrun error

Lovika Moudgil lovikamoudgil at gmail.com
Sun Aug 24 11:28:10 CEST 2014

Hi everyone ,

Need some help .I have got an error in my mdrun . Upto grompp every thing
was fine but when I give command for mdrun ,It stops with this ...
Steepest Descents:
   Tolerance (Fmax)   =  1.00000e+03
   Number of steps    =        10000
Step=   14, Dmax= 1.2e-06 nm, Epot=  2.08534e+18 Fmax=         inf, atom= 19
Energy minimization has stopped, but the forces have not converged to the
requested precision Fmax < 1000 (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)

writing lowest energy coordinates.

Steepest Descents converged to machine precision in 15 steps,
but did not reach the requested Fmax < 1000.
Potential Energy  =  2.0853354e+18
Maximum force     =            inf on atom 19
Norm of force     =  1.7429674e+18

constraints are all ready none ...Please help me what should I do to solve
this .
Thanks and Regards

More information about the gromacs.org_gmx-users mailing list