From: Jérôme Hénin (jerome.henin_at_ibpc.fr)
Date: Mon Apr 12 2021 - 08:53:14 CDT
Hi René,
>> MW-eABF is not that different from ABF, it's just that the ABF quantities
>> (mainly the biasing force itself) pertain to the extended coordinate. Those are
>> shared exactly as in standard mwABF, because they are represented the same way
>> in the implementation.
>> The data for the *unbiased free energy estimators* is a separate question: it is
>> not shared in the current state of the code, and in a sense it does not need to
>> be shared during the simulation, as these estimators are really a matter of
>> post-processing. Anything that is done on the fly is just for convenience.
> 1. Does that mean that the output of multiple replicas simulations (using shared
> (e)ABF) MUST be merged in order for results to be valid
> since for a single replica the "actually" applied biasing force does is
> different from the corresponding content of the (zcount/zgrad) output files
> produced by this walker?
The zcount/zgrad data for each walker is still valid for the given replica. As the simulation converges they should converge to the same final values across replicas, even without sharing.
> 2. What is actually printed to the outputname.grad/count file (named the same
> way as in plain abf output) when using eABF, this is the gradient/counts of the
> fictious particle, correct?
That is correct.
>>>>> * Then latest literature would be a bit misleading when stating usage of
>>>>> MW-eABF.
>> Is there something else than the QM/MM tutorial that mentions it?
> It is stated in the paper about WtM-eABF Method ( Taming Rugged Free Energy
> Landscapes Using an Average Force [
> https://urldefense.com/v3/__http://dx.doi.org/10.1021/acs.accounts.9b00473__;!!DZ3fjg!pkIvIjJO9NBIUsI0DIFDIqoEmOIR-ot_UY-KI0AJeqikGqC7TOCwTJ2CJzClaXl39A$
> | https://urldefense.com/v3/__http://dx.doi.org/10.1021/acs.accounts.9b00473__;!!DZ3fjg!uPMvYCFbbdXOyaMgjQOMbuuCd681Djcttd8uytDXrz09dJFFUsowi6-jGHVG9H8jxg$ ] )
Ah, indeed.
Jérôme
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