On January 17, 2011 at 2:21 PM "Justin A. Lemkul" <[email protected]> wrote:

>
>
> TJ Mustard wrote:
> >
> >
> > No this is a completely different error that occurs when the other (EM)
> > error does not.
> >
>
> So, EM completes, but you then get this unstable system?  How well did EM
> converge?  Were the potential and maximum force acceptable?
>
> Instabilities are generally caused by incorrect topologies or .mdp settings.
> Those are the first places I would look for sources of error.
>
> -Justin
>
> > 
> >
> > Thank you,
> >
> > TJ Mustard
> >
> > On January 17, 2011 at 1:51 PM "Justin A. Lemkul" <[email protected]> wrote:
> >
> >  >
> >  >
> >  > TJ Mustard wrote:
> >  > >
> >  > >
> >  > > Hi all,
> >  > >
> >  > >
> >  > >
> >  > > We have been running a lot of simulations on protein ligand
> >  > > interactions, and my settings/setup/mdp files worked great for one
> >  > > system. Then when we moved to a larger and more complicated system we
> >  > > started getting mdrun 1-4 interaction errors in our MD.
> >  > >
> >  > >
> >  > >
> >  > > We are running with heavyh and have correctly made our ligands with
> >  > > acpype and edited to have heavyh.
> >  > >
> >  > > Same setup as our smaller simpler model, but keep getting these:
> >  > >
> >  > >
> >  > >
> >  > > Warning: 1-4 interaction between X and Y at distance 1.804 which is
> >  > > larger than 1-4 table size 1.800 nm.
> >  > >
> >  > >
> >  > >
> >  > > The jobs will continue on and finish but we are worried about the error
> >  > > that could be included with these errors.
> >  > >
> >  > >
> >  >
> >  > Is this related to the other issue we're discussing?  If so, please
> > do not
> >  > double-post, especially if you're including different information in
> > different
> >  > threads.  It becomes a nightmare to try to keep track of.
> >  >
> >  > That particular error is usually not a good sign.  Normal, stable
> > simulations
> >  > should not give such an error.
> >  >
> >  > -Justin
> >  >

 

Here is the tail of my em:

Step= 3438, Dmax= 2.5e-04 nm, Epot= -1.05878e+06 Fmax= 8.91784e+01, atom= 43563
Step= 3439, Dmax= 3.0e-04 nm, Epot= -1.05878e+06 Fmax= 8.89898e+01, atom= 43563
Step= 3440, Dmax= 3.6e-04 nm, Epot= -1.05878e+06 Fmax= 3.27390e+02, atom= 24
Step= 3441, Dmax= 4.3e-04 nm, Epot= -1.05878e+06 Fmax= 3.34235e+02, atom= 24
Step= 3451, Dmax= 1.0e-06 nm, Epot= -1.05878e+06 Fmax= 3.32604e+02, atom= 24563
Stepsize too small, or no change in energy.
Converged to machine precision,
but not to the requested precision Fmax < 20

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 3452 steps,
but did not reach the requested Fmax < 20.
Potential Energy  = -1.0587850e+06
Maximum force     =  3.3423511e+02 on atom 24
Norm of force     =  4.9464898e+00

 

My major settings are:

 

define                   = -DPOSRES_WATER

integrator               = steep

nsteps                   = 10000

emtol                    = 20 
emstep                   = 0.01

 

Am I setting my emtol to low? I occasionally see a Fmax of ~250-900 but mostly above that.

 

 

I am currently having the epiphany that -DPOSRES_WATER could be my problem.

 

Thank you,

TJ Mustard

 

 

 

 

> >  > >
> >  > >
> >  > >
> >  > > Any help would be appreciated. Also I can attach my mdp files.
> >  > >
> >  > >
> >  > >
> >  > > Thank you,
> >  > >
> >  > > TJ Mustard
> >  > > Email: [email protected]
> >  > >
> >  >
> >  > --
> >  > ========================================
> >  >
> >  > Justin A. Lemkul
> >  > Ph.D. Candidate
> >  > ICTAS Doctoral Scholar
> >  > MILES-IGERT Trainee
> >  > Department of Biochemistry
> >  > Virginia Tech
> >  > Blacksburg, VA
> >  > jalemkul[at]vt.edu | (540) 231-9080
> >  > http://www.bevanlab.biochem.vt.edu/Pages/Personal/justin
> >  >
> >  > ========================================
> >  > --
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> >  >
> >
> > 
> >
> > TJ Mustard
> > Email: [email protected]
> >
>
> --
> ========================================
>
> Justin A. Lemkul
> Ph.D. Candidate
> ICTAS Doctoral Scholar
> MILES-IGERT Trainee
> Department of Biochemistry
> Virginia Tech
> Blacksburg, VA
> jalemkul[at]vt.edu | (540) 231-9080
> http://www.bevanlab.biochem.vt.edu/Pages/Personal/justin
>
> ========================================
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>

 

TJ Mustard
Email: [email protected]

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