On Thu, Apr 16, 2020 at 1:37 AM Wolfgang Verestek <
[email protected]> wrote:

>
>
> Am Mittwoch, 15. April 2020 14:55:59 UTC+2 schrieb Christoph Junghans:
>>
>>
>>
>> On Wed, Apr 15, 2020 at 6:36 AM Wolfgang Verestek <[email protected]>
>> wrote:
>>
>>> There is indeed a slight difference. but as stated before, i think
>>> qualitatively they are matching.
>>>
>>> Second thing: I increased the cutoff to be more than half the box (9 ->
>>> 15 A). This results in the behavior that we have seen before. Also the VMD
>>>
>> Ok, now I see, well the box size is 18.6 A, a cutoff of more than 9.3 A
>> isn't really physically meaningful and csg_stat should basically warn of
>> that.
>>
> ok, thanks. But could give me a hint why such a cutoff is physically not
> meaningful? I understand that such a small system does have bad statistics
> etc. but the particle is not self-interacting (although the molecule is,
> but it's also doing that with cutoff of 0.5* box length). Isn't that
> exactly what periodic boundaries should cover? I mean, extreme case here,
> but...?
>
Periodic boundaries follow minimum image convention, that means one only
counts minimum of all distances in all periodic images.
Imagine a 1D box of length L and put one particle at 0 and another at L/2.
Their distance will be L/2, but if you move it further away from 0, it will
come closer to the periodic image of the 1st particle sitting at L and
hence making the distance shorter again. In 3D there is another factor of
sqrt(3), but I think that is the reason why VMD had 0s in the rdf for
bigger distances.

Christoph

>
>
>>
>> Christoph
>>
>>>
>>>
>>> Am Mittwoch, 15. April 2020 14:13:30 UTC+2 schrieb Christoph Junghans:
>>>>
>>>>
>>>>
>>>> On Wed, Apr 15, 2020 at 6:05 AM Wolfgang Verestek <
>>>> [email protected]> wrote:
>>>>
>>>>>
>>>>>
>>>>> Am Mittwoch, 15. April 2020 14:00:32 UTC+2 schrieb Christoph Junghans:
>>>>>>
>>>>>>
>>>>>>
>>>>>> On Wed, Apr 15, 2020 at 05:56 Wolfgang Verestek <
>>>>>> [email protected]> wrote:
>>>>>>
>>>>>>>
>>>>>>>
>>>>>>> Am Mittwoch, 15. April 2020 13:52:01 UTC+2 schrieb Wolfgang Verestek:
>>>>>>>>
>>>>>>>>
>>>>>>>>
>>>>>>>> Am Dienstag, 14. April 2020 19:21:07 UTC+2 schrieb Christoph
>>>>>>>> Junghans:
>>>>>>>>>
>>>>>>>>>
>>>>>>>>>
>>>>>>>>> On Tue, Apr 14, 2020 at 8:40 AM Wolfgang Verestek wrote:
>>>>>>>>>
>>>>>>>>>> Dear Christoph,
>>>>>>>>>>
>>>>>>>>>> it seems to me, that the bonds in topology.xml do not influence
>>>>>>>>>> the result of csg_stat. On contrary, i got the same results 
>>>>>>>>>> regardless of
>>>>>>>>>> bonds being in topology.xml or not. The same is true for for wrapped 
>>>>>>>>>> or
>>>>>>>>>> unwrapped coordinates. The only thing that did change the result was
>>>>>>>>>> changing the cell size in the conf.gro by factor of 10 in each 
>>>>>>>>>> dimenstion
>>>>>>>>>> which looks like the nonperiodic results from Ovito (but made it 
>>>>>>>>>> necessary
>>>>>>>>>> to scale by a factor of 1000 to be in the same range of the plot).
>>>>>>>>>> Furthermore, i confirmed the results of Ovito by VMD. The nonperiodic
>>>>>>>>>> calculation in VMD oversitmates the first peak somewhat, but 
>>>>>>>>>> otherwise the
>>>>>>>>>> results are in good agreement. The results don't match perfectly, 
>>>>>>>>>> but as i
>>>>>>>>>> don't know how exactly VMD or Ovito compute the RDF i guess the 
>>>>>>>>>> match is
>>>>>>>>>> good enough and the drop in the periodic VMD plot should be due to 
>>>>>>>>>> some
>>>>>>>>>> other reason (maybe the g(r) plugin is limited to 3/4 cell lengt or 
>>>>>>>>>> sth.).
>>>>>>>>>> regarding scg_stat it still seems to me that the tail is smoothed
>>>>>>>>>> or periodic images in different directions are omitted. Could that 
>>>>>>>>>> be? I
>>>>>>>>>> can provide the files f necessary.
>>>>>>>>>>
>>>>>>>>> Ok now I am getting really confused, I just did a quick comparison
>>>>>>>>> of gmx rdf and csg_stat and the results are right on top of each 
>>>>>>>>> other.
>>>>>>>>>
>>>>>>>>> Could you do me a favor and try to follow:
>>>>>>>>> ```
>>>>>>>>> apt-get install gromacs
>>>>>>>>> cp /usr/share/gromacs/top/spc216.gro .
>>>>>>>>> wget
>>>>>>>>> https://raw.githubusercontent.com/votca/csg/master/src/tools/references/spce/sources/grompp.mdp
>>>>>>>>> wget
>>>>>>>>> https://raw.githubusercontent.com/votca/csg/master/src/tools/references/spce/sources/topol.top
>>>>>>>>> gmx grompp -c spc216.gro -maxwarn 1
>>>>>>>>> echo q | gmx make_ndx -f spc216.gro
>>>>>>>>> echo -e "1\n1" | gmx rdf -f spc216.gro -s topol.tpr -n index.ndx
>>>>>>>>> -selrpos mol_com -seltype mol_com -bin 0.02
>>>>>>>>> wget
>>>>>>>>> https://raw.githubusercontent.com/votca/csg/master/src/tools/references/spce/mapping.xml
>>>>>>>>> wget
>>>>>>>>> https://raw.githubusercontent.com/votca/csg/master/src/tools/references/spce/settings_rdf.xml
>>>>>>>>> csg_stat --options settings_rdf.xml --top  topol.tpr --trj
>>>>>>>>> spc216.gro --cg mapping.xml
>>>>>>>>> csg_map --top  topol.tpr --trj spc216.gro --cg mapping.xml --out
>>>>>>>>> cg.dump
>>>>>>>>> ```
>>>>>>>>> and then calculate the rdf from cg.dump with ovito and vmd and
>>>>>>>>> compare them with rdf.xvg and CG-CG.dist.new.
>>>>>>>>>
>>>>>>>>> Christoph
>>>>>>>>>
>>>>>>>>
>>>>>>>> Ovito and VMD give nearly the same results (green X / blue square).
>>>>>>>> I'm not sure how those two really compute the RDF. For Ovito I can set 
>>>>>>>> the
>>>>>>>> cutoff and the number of bins (9.0, 45) and i think the bin center is 
>>>>>>>> on
>>>>>>>> the x coordinates. In VMD i can set the cutoff and the delta (9, 0.2). 
>>>>>>>> As
>>>>>>>> said, i'm not sure how the bins are decided inside those two progs, so 
>>>>>>>> this
>>>>>>>> might lead to small offsets.
>>>>>>>> cg_stat on the other hand is a little bit off compared to ovito and
>>>>>>>> vmd. But this could be imho due to the binning as mentioned before.
>>>>>>>> qualitatively i think it's pretty much the same.
>>>>>>>>
>>>>>>> You can pick the bins size for csg_stat in settings_rdf.xml and for
>>>>>> gmx on command line so you can make it same as vmd for the comparison.
>>>>>>
>>>>>> Christoph
>>>>>>
>>>>>
>>>>> bin size is the same. 0.2 in vmd, 0.02 in settings_rdf.xml.
>>>>> I forgot the plot in the last post
>>>>>
>>>> Hmm, but it seems the dots are not at the same r values, or am I seeing
>>>> this wrong?
>>>>
>>>> Christoph
>>>>
>>>>>
>>>>>
>>>>>>>> - regards
>>>>>>>> Wolfgang
>>>>>>>>
>>>>>>> forgot the plot
>>>>>>>
>>>>>>>>
>>>>>>>>
>>>>>>>>
>>>>>>>>>
>>>>>>>>>
>>>>>>>>>>
>>>>>>>>>> Am Mittwoch, 8. April 2020 18:17:20 UTC+2 schrieb Christoph
>>>>>>>>>> Junghans:
>>>>>>>>>>>
>>>>>>>>>>>
>>>>>>>>>>>
>>>>>>>>>>> On Wed, Apr 8, 2020 at 5:01 AM Wolfgang Verestek <
>>>>>>>>>>> [email protected]> wrote:
>>>>>>>>>>>
>>>>>>>>>>>>
>>>>>>>>>>>>
>>>>>>>>>>>> Am Mittwoch, 8. April 2020 02:07:39 UTC+2 schrieb Christoph
>>>>>>>>>>>> Junghans:
>>>>>>>>>>>>>
>>>>>>>>>>>>>
>>>>>>>>>>>>>
>>>>>>>>>>>>> On Tue, Apr 7, 2020 at 9:59 AM Wolfgang Verestek <
>>>>>>>>>>>>> [email protected]> wrote:
>>>>>>>>>>>>>
>>>>>>>>>>>>>> Dear Christoph,
>>>>>>>>>>>>>>
>>>>>>>>>>>>>> thanks for your fast response. i followed you suggestion,
>>>>>>>>>>>>>> renamed the files and added the box tag to the topology file 
>>>>>>>>>>>>>> (files
>>>>>>>>>>>>>> attached). But the result stays the same. So, as you said that 
>>>>>>>>>>>>>> gromacs
>>>>>>>>>>>>>> format is better supported i changed my output to gro87 format. 
>>>>>>>>>>>>>> No errors,
>>>>>>>>>>>>>> but the discrepancy remains, regardless if i'm using wrapped or 
>>>>>>>>>>>>>> unwrapped
>>>>>>>>>>>>>> coords in the conf.gro file. See below. Are there any other 
>>>>>>>>>>>>>> things i could
>>>>>>>>>>>>>> change? Another format?
>>>>>>>>>>>>>> Is it possible to set the boundary conditions somewhere
>>>>>>>>>>>>>> specifically? Or could it be that periodic images of the 
>>>>>>>>>>>>>> specific atoms are
>>>>>>>>>>>>>> ignored (the simulation box is kind of small and close by region 
>>>>>>>>>>>>>> seems ok)?
>>>>>>>>>>>>>>
>>>>>>>>>>>>> Sorry, I didn't have time to look at your files yet, but does
>>>>>>>>>>>>> OVito handle exclusion in the same way as VOTCA?
>>>>>>>>>>>>> Have a look at the output of "csg_dump --top topology.xml
>>>>>>>>>>>>> --excl"
>>>>>>>>>>>>>
>>>>>>>>>>>>
>>>>>>>>>>>> How should that look like? I'm not sure if i understand that
>>>>>>>>>>>> format correctly, but it seems correct to me. in my data file Atom 
>>>>>>>>>>>> with id
>>>>>>>>>>>> 1 is connectod to atoms 2 3 4 and 36. I assume this is non 
>>>>>>>>>>>> repetitive so id
>>>>>>>>>>>> 4 does not show up again for atom id 4 and so on. I did not check 
>>>>>>>>>>>> the whole
>>>>>>>>>>>> list, but the first 10 lines are correct.
>>>>>>>>>>>>
>>>>>>>>>>>> I have 164 beads in 1 molecules
>>>>>>>>>>>>
>>>>>>>>>>>> List of exclusions:
>>>>>>>>>>>> 1 2 3 4 36
>>>>>>>>>>>>
>>>>>>>>>>> This means the atom #1 is excluded with atom #2, #3,#4 and #36
>>>>>>>>>>> and hence contributions from these pairs won't go into the RDF.
>>>>>>>>>>> VOTCA automatically created exclusion (in same way as Gromacs
>>>>>>>>>>> does) for bonds, angles and dihedrals.
>>>>>>>>>>>
>>>>>>>>>>> Christoph
>>>>>>>>>>>
>>>>>>>>>>>
>>>>>>>>>>>> 4 5 6 7
>>>>>>>>>>>> 7 8 9 10
>>>>>>>>>>>> 10 11 12
>>>>>>>>>>>> 12 13 14
>>>>>>>>>>>> 14 15 16 17
>>>>>>>>>>>> 17 18 19 39
>>>>>>>>>>>> 20 21 22 23 77
>>>>>>>>>>>> ...
>>>>>>>>>>>>
>>>>>>>>>>>>
>>>>>>>>>>>>> Secondly you could use "csg_map --top topology --no-map --trj
>>>>>>>>>>>>> lammps.dump --out out.pdb", to check if the coordinates are read 
>>>>>>>>>>>>> correctly.
>>>>>>>>>>>>>
>>>>>>>>>>>> apart from the bigger cell for the pdb (where this information
>>>>>>>>>>>> is not included) the positions look ok. (lammps file in "black 
>>>>>>>>>>>> cores", pdb
>>>>>>>>>>>> in transparent green).
>>>>>>>>>>>>
>>>>>>>>>>>>>
>>>>>>>>>>>>> Christoph
>>>>>>>>>>>>>
>>>>>>>>>>>>>>
>>>>>>>>>>>>>> Is there a way to visualize the xml or gro files? I know vmd,
>>>>>>>>>>>>>> but that segfaults when reading the gro file.
>>>>>>>>>>>>>>
>>>>>>>>>>>>>> Ultimately the whole thing should go into force matching. But
>>>>>>>>>>>>>> i guess the results will be off if already the RDF is wrong?
>>>>>>>>>>>>>>
>>>>>>>>>>>>>> Is it really necessary to have one file per molecule type and
>>>>>>>>>>>>>> what distinguishes different molecule types? If i have several 
>>>>>>>>>>>>>> PA6
>>>>>>>>>>>>>> molecules with different length/count of monomers is that 
>>>>>>>>>>>>>> already different
>>>>>>>>>>>>>> molecules?
>>>>>>>>>>>>>>
>>>>>>>>>>>>>> Thanks and regards
>>>>>>>>>>>>>> Wolfgang
>>>>>>>>>>>>>>
>>>>>>>>>>>>>>
>>>>>>>>>>>>>>
>>>>>>>>>>>>>> --
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>>>>>>>>>>>>>> .
>>>>>>>>>>>>>>
>>>>>>>>>>>>>
>>>>>>>>>>>>>
>>>>>>>>>>>>> --
>>>>>>>>>>>>> Christoph Junghans
>>>>>>>>>>>>> Web: http://www.compphys.de
>>>>>>>>>>>>>
>>>>>>>>>>>> --
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>>>>>>>>>>>> .
>>>>>>>>>>>>
>>>>>>>>>>>
>>>>>>>>>>>
>>>>>>>>>>> --
>>>>>>>>>>> Christoph Junghans
>>>>>>>>>>> Web: http://www.compphys.de
>>>>>>>>>>>
>>>>>>>>>> --
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>>>>>>>>>> .
>>>>>>>>>>
>>>>>>>>>
>>>>>>>>>
>>>>>>>>> --
>>>>>>>>> Christoph Junghans
>>>>>>>>> Web: http://www.compphys.de
>>>>>>>>>
>>>>>>>> --
>>>>>>> Join us on Slack: https://join.slack.com/t/votca/signup
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>>>>>>> .
>>>>>>>
>>>>>> --
>>>>>> Christoph Junghans
>>>>>> Web: http://www.compphys.de
>>>>>>
>>>>> --
>>>>> Join us on Slack: https://join.slack.com/t/votca/signup
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>>>>> .
>>>>>
>>>>
>>>>
>>>> --
>>>> Christoph Junghans
>>>> Web: http://www.compphys.de
>>>>
>>> --
>>> Join us on Slack: https://join.slack.com/t/votca/signup
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>>> .
>>>
>>
>>
>> --
>> Christoph Junghans
>> Web: http://www.compphys.de
>>
>> --
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-- 
Christoph Junghans
Web: http://www.compphys.de

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