[gmx-users] step size too small
tsjerkw at gmail.com
Mon Jun 30 11:32:17 CEST 2008
Please do read the following:
This one's in there.
On Mon, Jun 30, 2008 at 11:26 AM, minnale <minnale_gnos at rediffmail.com> wrote:
> Hi all,
> 1) I have embedded protein into popcbilayer
> 2) Energy minimisation
> 3) Later added ions by using genion,
> 4) When I am trying to run minimisation its showing following sentences
> Stepsize too small, or no change in energy.
> Converged to machine precision,
> but not to the requested precision Fmax < 100
> 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 49 steps,
> but did not reach the requested Fmax < 100.
> Potential Energy = -2.1825061e+05
> Maximum force = 4.3672461e+03 on atom 7008
> Norm of force = 5.5597691e+04
> my .mdp file is
> cpp = /usr/bin/cpp
> define = -DFLEX_SPC
> constraints = none
> integrator = steep
> nsteps = 500
> ; Energy minimizing stuff
> emtol = 100
> emstep = 0.01
> nstcomm = 1.0
> ns_type = grid
> rlist = 1.0
> rcoulomb = 1.0
> rvdw = 1.0
> When I run minimisation before adding ions it ran fine but later not why?
> I have searched about solve this problem in archives list and I understood
> that this not an error. Can I proceed further simulations
> Any comments will be appreciated.
> Thanks in advance.
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Tsjerk A. Wassenaar, Ph.D.
Junior UD (post-doc)
Biomolecular NMR, Bijvoet Center
3584 CH Utrecht
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