[gmx-users] Re: Minimization not converging

Jack Shultz jshultz at hydrogenathome.org
Thu Mar 12 16:01:13 CET 2009

I should have included some output

Step=   32, Dmax= 2.4e-06 nm, Epot= -1.03223e+05 Fmax= 3.87326e+06, atom= 25439
Step=   33, Dmax= 1.2e-06 nm, Epot= -1.03222e+05 Fmax= 3.87334e+06, atom= 25439
Stepsize too small, or no change in energy.
Converged to machine precision,
but not to the requested precision Fmax < 10

Double precision normally gives you higher accuracy.
You might need to increase your constraint accuracy, or turn
off constraints alltogether (set constraints = none in mdp file)

writing lowest energy coordinates.

Steepest Descents converged to machine precision in 34 steps,
but did not reach the requested Fmax < 10.
Potential Energy  = -1.4354568e+06
Maximum force     =  6.9535597e+10 on atom 25439
Norm of force     =  4.5592896e+08

More details here.

On Thu, Mar 12, 2009 at 10:59 AM, Jack Shultz
<jshultz at hydrogenathome.org> wrote:
> Hi,
> I think that my minimization are not running long enough. I've been
> following the parameters in tutorials but it seems like they all die
> at 34 steps
> I've been using these tutorials
> https://extras.csc.fi/chem/courses/gmx2007/tutorial1/tutorial1.pdf
> http://md.chem.rug.nl/education/mdcourse/MDpract.html
> Its been the same case for me regardless to whether I use Windows or
> Linux platforms. Are there settings I can use to make the simulation
> minimize longer or is this case where I need to have double precision
> version?
> --
> Jack
> http://www.facebook.com/home.php#/profile.php?id=832713248
> http://hydrogenathome.org



More information about the gromacs.org_gmx-users mailing list