[gmx-users] Re: Re[7]: Flat energy profile in g_wham

[chris.neale at utoronto.ca]

So now we have the first real lead. Next is for you to simplify your  
system to the point where you *can* understand the relationship  
between the pullf and pullx files. For example, I always suggest a  
water bath of explicit water with the sd integrator and apply the pull  
code to two waters.

It's time for you to bash your head against this one on your own until  
you can find a simple system that has no problem and then a slightly  
more complex system that has the problem. Bring those back to the list  
and we can help again if you can;t figure it out.

PS: you should file a bugzilla or otherwise try to get the gromacs  
list fixed so that you can post directly.

Chris.

Quoting alexander yakovenko <yakovenko_a at ukr.net>:

>  Sorry for mixing things, I do pull into N Y N direction and then
>    performed umbrella simulation at Y Y Y for each distances window.
>    This is very good question, actually I don't realize it too. The only
>    thing what I can say is that I haven't edited/renamed these files,
>    just copy them. So this is pure output of mdrun, hopes it knows what
>    it writes... I can provide a tpr of a window for example so you can
>    check couple first strings (for reproduction, I carried out all
>    calculations on 8x Xeons at 2.66 workstations).
>    Alex
>    >
>
>    First, you confuse me when you say "pulling direction was along
>    Y-axis" since your .mdp file indicates pull_dim = Y Y Y and so you are
>    pulling in *all* dimensions.
>
>    Your profile doesn't look like mine at all, but then again I took mine
>    from a force profile. Now that I can see your forces and
>    displacements, I can't find any match between them. For example:
>    cneale at cneale-desktop:~/work/August2010/integral/u10$ tail pullf_u10.xvg
>    11982.0000      255.769
>    11984.0000      332.586
>    11986.0000      291.367
>    11988.0000      264.031
>    11990.0000      330.69
>    11992.0000      336.757
>    11994.0000      327.46
>    11996.0000      475.078
>    11998.0000      440.766
>    12000.0000      342.814
>    cneale at cneale-desktop:~/work/August2010/integral/u10$ tail pullx_u10.xvg
>    11982.0000      3.05189 4.39188 -1.23643        2.03259 2.62201 3.35563
>    11984.0000      3.12086 4.37951 -1.63297        1.98567 2.64212 -3.25943
>    11986.0000      3.13274 4.37699 -1.57303        1.97354 2.64089 -3.32607
>    11988.0000      3.13754 4.38542 -1.52275        1.94917 2.63444 -3.38366
>    11990.0000      3.12712 4.38416 -1.61647        1.93608 2.63691 -3.29597
>    11992.0000      3.11342 4.37694 -1.59735        1.95931 2.61705 -3.28952
>    11994.0000      3.0957  4.384   -1.5691 1.99226 2.57634 -3.3149
>    11996.0000      3.08384 4.38684 5.24141 2.00727 2.57168 -3.09875
>    11998.0000      2.99618 4.41111 5.25558 2.08776 2.53869 -3.1227
>    12000.0000      2.79826 4.41958 5.22444 2.29862 2.53084 -3.12472
>
>
>    Can you explain to me how these can match up (with an equation please)?
>
>
>    Quoting alexander yakovenko <   yakovenko_a at ukr.net   >:
>
>    > Yep, it was mistake with a sign, is
>    >      
> http://picasaweb.google.ca/117558205101329348732/G_wham#5511351478636719042
>    > looks like your one? Btw my temperature was 310K.
>    > The dollars you would lost (as I used only 1 mdp for all runs via
>    > script and thus avoiding humans mistakes like with pictures) is
>    > probably because complicated landscape - the dissociation is coupled
>    >  to (partial) unfolding and relative sub-domains shift (actually
>    > this  experiment is aimed to support this hypothesis). I.e. it does
>    > not  look too suspicious for me; something closer to manual was
>    > expected  though. Anyway I attach logs from all my simulations and
>    > the mdp.
>    > As for box, it has 10x16x7 edges and pulling direction was along
>    > Y-axis to bring molecules only 5.5nm apart (DNA and protein of ~2 nm
>    >  radii) so there is definitely sufficient distances.
>    > Anyway the only bug in g_wham is an explanation I can give to
>    > ABSOLUTELY flat line of PMF profile.
>    > As for colors, can we please stick on windows ids instead? I guess
>    > you told about w4, w6 and w8 so I attached their logs from mdrun and
>    >  for w10 too.
>    > P.S. I still not understand if there is a way to make g_wham working
>    >  for me (suggesting all other calculations were made fairly)?
>    > Alex
>    >
>