[gmx-users] Umbrella Sampling

[Gavin Melaugh]

Cheers Chris

If I remove the red histogram (the first of the wider distributions),
which should be centred around 0.80nm but is actually centred around
0.78 nm; and add in some more histograms with higher force constants the
profile changes slightly. It seems that  g_wham is very sensitive to
these subtleties. How do I know which curve is correct? I have about six
such curves that differ slightly in this manner.

Gavin

chris.neale at utoronto.ca wrote:
> looks fine to me, no need to do that extra sampling that I suggested
> since it appears that you already did this -- benefits of seeing real
> data ;). If you want to understand why your histograms are not always
> centered at r0 (note that this is just fine) then you should read more
> about US, WHAM, and how to bias/debias the data for US (I am sure that
> there are textbooks around that explain this). The only case in which
> all of your histograms will be centered at their respective r0 is when
> the underlying PMF is exactly flat.
>
> Chris.
>
> -- original message --
>
> Hi Chris many thanks again for the advise. I have, or at least I thought
> have sampled my barrier region to death, but as I say some histograms
> may not be centred around r0. I will proceed with what you suggest.
> Please find attached a picture of the histograms, the corresponding
> profile, and a sample mdp file that I use.
>
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