2016-05-18 11:56 GMT-06:00 Takahiro Ohkuma <[email protected]>:
> Dear Christoph
>
> Thank you for your suggestions. Unfortunately, I found it was difficult for
> me to find out a clue in the votca source codes.
>
> In the csg_boltzmann conmmand, I could obtain a smooth profile on condition
> that "periodic = 1". There are no jumps at the data ends.
> Is it possible to turn on the periodic option during ibi process?
Can you check if the following patch helps:
<https://github.com/votca/csg/commit/63f8d822187142dc82f3787dd2211a282e39b85b>

Christoph
> Or, can Votoca omit two data at both ends during ibi?
>
> Best regards
> Takahiro
>
>
>
> 2016年5月12日木曜日 19時07分37秒 UTC+2 Christoph Junghans:
>>
>> 2016-05-11 10:47 GMT-06:00 Takahiro Ohkuma <[email protected]>:
>> > Dear Christoph
>> >
>> > Thank you very much for your prompt reply!
>> > I am doing short simulations becase I have not tried the numbers you
>> > suggested. I would like to share the results once I get them.
>> >
>> > I have seen a similar behavior when I made the dihedral potential
>> > through
>> > boltzmann inversion by using csg_boltzmann.
>> If this is happening in csg_boltzmann as well, it sounds like a
>> problem in the histogram class.
>>
>> > At that time, I clipped the edges as a poorly sampled region.
>> >
>> > Takahiro
>> >
>> > 2016年5月11日水曜日 17時17分56秒 UTC+2 Christoph Junghans:
>> >>
>> >> 2016-05-11 4:35 GMT-06:00 Takahiro Ohkuma <[email protected]>:
>> >> > Dear all
>> >> >
>> >> > I am trying IBI for the bonded interactions of my polymer because the
>> >> > bonded
>> >> > potentials obtained by a single-chain simulation in vacuum did not
>> >> > well
>> >> > reproduce the bond distributions in the melt.
>> >> >
>> >> > According to the tutorial of "hexane/ibi_bonded", I made a
>> >> > setting.xml
>> >> > and
>> >> > prepared other files.
>> >> > But, at the calculation of dihedral distribution in the IBI steps, I
>> >> > always
>> >> > meet a strange sharp peak at an edge of the distribution (one data
>> >> > point) as
>> >> > the attached png file. This gives a sharp dihedral potential at the
>> >> > edge,
>> >> > and then the next simulation often diverges.
>> >> > Although I tried other values of <min>, <max>, and <step>, the
>> >> > situation
>> >> > did
>> >> > not changed.
>> >> > Is there any ways to manage this peak in the setting.xml?
>> >> Your settings.xml look correct to me!
>> >>
>> >> IBI for dihedrals isn't very well test and it looks to me there is an
>> >> issue with boundary conditions, i.e. dihedrals are periodic.
>> >> Did you try to set max=-min=2.5, or min=0.5 and max= 2pi-0.5?
>> >>
>> >> Looking at the distribution, it seems the bug is in csg_stat itself. I
>> >> guess the problem is here:
>> >>
>> >> <https://github.com/votca/csg/blob/master/src/tools/csg_stat_imc.cc#L400>
>> >> It is marked as a TODO ;-)
>> >> However, the normalization should not matter as IBI does a ratio of
>> >> the distributions, but for the periodic histograms there might be a
>> >> round off error.
>> >>
>> >> Christoph
>> >>
>> >>
>> >>
>> >> >
>> >> > Best regards
>> >> > Takahiro
>> >> >
>> >> > --
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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

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