Re: reconstructing pmf

From: Jeff Comer (
Date: Tue Dec 19 2017 - 09:20:57 CST

I just wanted to note that the error you're experiencing "differs
greatly from the value last read from the state file" can be due to
the restartFreq in the NAMD configuration file being different from
colvarsRestartFrequency in the Colvars configuration file. The
simulation then starts from a different frame from the last one in the
state file and the value of the colvar is likely to be different. If
this is the reason, one solution is simply to edit the .colvars.state
file and change the value of the colvar to the calculated value


Jeffrey Comer, PhD
Assistant Professor
Institute of Computational Comparative Medicine
Nanotechnology Innovation Center of Kansas State
Kansas State University
Office: P-213 Mosier Hall
Phone: 785-532-6311

On Tue, Dec 19, 2017 at 8:08 AM, Giacomo Fiorin
<> wrote:
> Hi Stefano, I wouldn't try turning on or off the PBC- and wrapping-related
> flags, but try instead to diagnose what is going on.
> You could load the same set of input files in VMD:
> mol new *.psf
> mol addfile *.restart.coor
> pbc readxst *.restart.xsc
> (The last one is needed to load the PBC unit cell.) Then load the Colvars
> configuration file and evaluate the variables as you did before.
> If you conclude that PBC wrapping is to blame, keep in mind that disabling
> wrapAll can only prevent future problems. Once the existing restart files
> written by NAMD are affected by it, you will probably need to go back to the
> 2nd most recent set of restart files. Alternatively, you could opt for
> translating and re-wrapping your system in VMD using pbctools, or the much
> faster qwrap:
> Then, you can save back the corrected restart file:
> animate write namdbin wrapped.coor
> If you do this you lose the double precision, but it would only be for that
> one step when you restart.
> Giacomo
> On Tue, Dec 19, 2017 at 3:48 AM, Stefano Guglielmo
> <> wrote:
>> Hi Josh and Giacomo,
>> thanks for tips. I tried to re-run tha calculation loading
>> *.restart.colvars.state in the config file, but NAMD is reporting the
>> following error:
>> Error: the calculated value of colvar "distance_ver":
>> colvars: 44.0519
>> colvars: differs greatly from the value last read from the state file:
>> colvars: 60.976
>> colvars: Possible causes are changes in configuration, wrong state file,
>> or how PBC wrapping is handled.
>> I double checked the requested files but apparently everything seems
>> correct;
>> I also tried with wrapall off and forceNoPBC for the collective variable
>> involved in the error, but the outcome was always the same.
>> Do you have any suggestions?
>> Thanks
>> Stefano
>> 2017-12-19 2:40 GMT+01:00 Giacomo Fiorin <>:
>>> If you do have the state file saved, the next run after loading it should
>>> print the PMF file again.
>>> Giacomo
>>> On Dec 18, 2017 7:38 PM, "Vermaas, Joshua" <>
>>> wrote:
>>>> Hi Stefano,
>>>> I haven't done it myself, but wouldn't you just need to write a script
>>>> to re-add the hills that metadynamics is adding yourself, based either on
>>>> the colvars.traj file (ideally) or worst case recalculating your reaction
>>>> coordinate trajectory from the dcd? The end result should in principle be
>>>> the same if you saved these values at the same frequency that hills are
>>>> added, albeit with a large chance of making a mistake somewhere in code if
>>>> you don't have a working example to make sure that your script does what it
>>>> is supposed to.
>>>> -Josh
>>>> On 12/18/2017 05:29 PM, Stefano Guglielmo wrote:
>>>> Dear NAMD users,
>>>> is it possible to reconstruct pmf of a metadynamics simulation (if for
>>>> some reason the original file was corrupted or lost) in the same format as
>>>> the one written as output by NAMD?
>>>> Thanks in advance
>>>> Stefano
>>>> --
>>>> Stefano GUGLIELMO PhD
>>>> Assistant Professor of Medicinal Chemistry
>>>> Department of Drug Science and Technology
>>>> Via P. Giuria 9
>>>> 10125 Turin, ITALY
>>>> ph. +39 (0)11 6707178
>> --
>> Stefano GUGLIELMO PhD
>> Assistant Professor of Medicinal Chemistry
>> Department of Drug Science and Technology
>> Via P. Giuria 9
>> 10125 Turin, ITALY
>> ph. +39 (0)11 6707178
> --
> Giacomo Fiorin
> Associate Professor of Research, Temple University, Philadelphia, PA
> Contractor, National Institutes of Health, Bethesda, MD

This archive was generated by hypermail 2.1.6 : Mon Dec 31 2018 - 23:20:45 CST