Re: [AMBER] Stricter convergence Criterion for stretching

From: Adrian Roitberg <roitberg.ufl.edu>
Date: Tue, 25 Apr 2017 14:01:02 -0400

Hi

There is no convergence at all in the calculation you sent.

You are asking the system to RUN for a full 6500 steps, and apply a
restraint for that distance to 41A.

It will not stop when it gets to 41, it will stop only after 6500 steps.

That is why you get entries in the DUMPAVE up to 6500

Do not look at the mdinfo file, it is only updated once per minute I
believe.

Look at your mdout file instead.

adrian



On 4/25/17 1:57 PM, Ramin Salimi wrote:
> Dear Amber users
>
> I am trying to stretch my DNA molecule for 1A0 from its current value which is 40A0 to 41A0. So I used nmropt by the application of strict restraint. This restraint consisted of a parabolic well with a force constant of 100 kcal/mol/Å2 using the following dist file:
>
> &rst
> iat=2,382, r1=0, r2=41, r3=41, r4=999, rk2 = 100.0, rk3 = 100.0, /
>
> Is this dist. file correct to apply a parabolic well with that 100 kcal/mol/Å2?
>
> And the mdin file was as such:
>
> &cntrl
> imin = 0, nstlim = 6500, dt = 0.002,
> ntx = 5, tempi = 300.0, temp0 = 300.0,
> ntt = 3, gamma_ln=5.0
> ntc = 2, ntf = 2, ntb = 2, ntp = 1,
> ntwx = 100, ntwr = 100, ntpr = 100,
> ntwv = 100, ntwf = 100, ntwe = 100,
> cut = 8.0, ig=-1, ioutfm=1,
> irest = 1, nmropt=1,
>
> &end
> /
> &wt type='DUMPFREQ', istep1=5 /
> &wt type='END' /
> DISANG=dist_nmropt.RST
> DUMPAVE=dist_vs_nmropt
> LISTIN=POUT
> LISTOUT=POUT
> /
>
> When I checked the info file, it showed just 100 steps out of 6500 was completed, which I believe shows it has converged. Is there any way to implement a stricter convergence criterion so it takes longer than just 100 steps?
>
> Also when I check the DUMPAVE file, it shows me the value of the restraint up to step number 6495. If it was cut at step #100 based on the info file, why is it showing the restraint values up to step #6495??
>
> Any help is greatly appreciated
>
> Thanks
>
> Ramin
>
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-- 
Dr. Adrian E. Roitberg
University of Florida Research Foundation Professor
Department of Chemistry
University of Florida
roitberg.ufl.edu
352-392-6972
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Received on Tue Apr 25 2017 - 11:30:02 PDT
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