[gmx-users] energy minimization - not converge

[Mark Abraham]

leila karami wrote:
> Hi
> 
> I want to do energy minimization but follow subject is came up:
> 
> writing lowest energy coordinates.
> 
> Back Off! I just backed up ooo.gro to ./#ooo.gro.5#
> 
> Steepest Descents did not converge to Fmax < 2000 in 101 steps.
> Potential Energy  = -3.2421097e+05
> Maximum force     =  1.4766100e+04 on atom 1441
> Norm of force     =  2.5146213e+02
> 
> my em.mdp file is:

I doubt it - the above output claims the use of integrator = steep and 
nsteps = 100, unlike the below. Computers and science are very exacting, 
and you need to be also when you work with both of them!

> cpp                 =  /usr/bin/cpp
> define              =  -DFLEX_SPC
> constraints         =  none
> integrator          =  cg
> nsteps              =  100
> ;
> ; Energy minimizing stuff
> ;
> emtol               =  2000
> emstep              =  0.01
> 
> nstcomm             =  1
> ns_type             =  grid
> rlist               =  1
> rcoulomb            =  1.0
> rvdw                =  1.0
> Tcoupl              =  no
> Pcoupl              =  no
> gen_vel             =  no
> 
> I changed nsteps to 1000, 2000 and 10000. also I changed emtol to 500 
> but same error came up again.

Changing this file won't help - change the correct one. Getting output 
with the same maximum number of steps was a good hint that you're using 
the same input...

Mark