I think the output from WHAM in the terminal may give some information to
detect the problem.
WHAM will tell you the boundary he used to fit your PMF because your
histogram and COM position both tell us your reaction coordinate is range
from about 2-7nm but WHAM fit from 0-10nm is so strange
Best regards,

On Tue, Apr 21, 2020 at 4:49 PM Justin Lemkul <jalem...@vt.edu> wrote:

>
>
> On 4/21/20 10:40 AM, Rolly Ng wrote:
> > Dear Justin,
> >
> > I cut the x-axis to 8nm but I have uploaded the original histogram plot
> to
> > RG. Please have a look again, thank you.
>
> It's not a matter of changing the axis. Your histograms indicate
> sampling from 2 - 8 nm. Your PMF is computed from 0 - 10 nm. If you have
> a protein-protein complex, I doubt the COM distance can ever be zero.
> There is a disconnect between your files.
>
> -Justin
>
> > I used the following command for wham,
> > gmx wham -it tpr-files.dat -if pullf-files.dat -o -hist -unit kCal
> >
> > I used the AMBER99SB-ILDN forcefield and protein protein pair is
> KEAP1-NRF2
> > (2FLU) from https://www.rcsb.org/structure/2FLU
> >
> > I tried to pull the NRF2 from KEAP1, and I can visualize that it has been
> > successfully pulled from the initial position, producing the force and
> COM
> > plots which seem reasonable.
> >
> > How can I debug the problem? Which files should I check?
> >
> > Thanks,
> > Rolly
> >
> > -----邮件原件-----
> > 发件人: gromacs.org_gmx-users-boun...@maillist.sys.kth.se
> > <gromacs.org_gmx-users-boun...@maillist.sys.kth.se> 代表 Justin Lemkul
> > 发送时间: 2020年4月21日星期二 下午7:09
> > 收件人: Discussion list for GROMACS users <gmx-us...@gromacs.org>
> > 主题: Re: [gmx-users] Problem with Potential Mean Force calculation
> >
> >
> >
> > On 4/21/20 2:08 AM, Rolly Ng wrote:
> >> Dear Gromacs user and Dr. lemkul,
> >>
> >> I think my previous email is too large to send on the list. Could you
> >> please kindly look at the link for the plots?
> >>
> >> https://www.researchgate.net/post/GROMACS_2020_pull_code_produces_stra
> >> nge_Potential_Mean_Force_PMF_result
> >>
> > I don't see how the PMF could possibly arise from your data. The reaction
> > coordinate extends from 2 - 6 nm, but your PMF plot goes from 0
> > - 10 nm.
> >
> >> I tried to applied the umbrella tutorial to my protein-protein system,
> >> and I am using GROMACS 2020
> >>
> >> http://www.mdtutorials.com/gmx/umbrella/index.html
> >>
> >> I have very dense windows to 0.1nm as shown on the attached histogram,
> >> but as I look at the PMF curve, it is strange and incomplete?
> >>
> > I hope you're not directly applying the tutorial; there are some aspects
> of
> > it (use of restraints, the window spacing, and the restraint only along
> z)
> > that are not applicable to general protein-protein complexes.
> >
> >> Could you please help me to check what has gone wrong?
> >>
> > What was your gmx wham command? I really don't understand how it could
> have
> > even produced that PMF given the data you have in the histograms.
> >
> > -Justin
> >
> > --
> > ==================================================
> >
> > Justin A. Lemkul, Ph.D.
> > Assistant Professor
> > Office: 301 Fralin Hall
> > Lab: 303 Engel Hall
> >
> > Virginia Tech Department of Biochemistry
> > 340 West Campus Dr.
> > Blacksburg, VA 24061
> >
> > jalem...@vt.edu | (540) 231-3129
> > http://www.thelemkullab.com
> >
> > ==================================================
> >
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> --
> ==================================================
>
> Justin A. Lemkul, Ph.D.
> Assistant Professor
> Office: 301 Fralin Hall
> Lab: 303 Engel Hall
>
> Virginia Tech Department of Biochemistry
> 340 West Campus Dr.
> Blacksburg, VA 24061
>
> jalem...@vt.edu | (540) 231-3129
> http://www.thelemkullab.com
>
> ==================================================
>
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> Gromacs Users mailing list
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