On Fri, Dec 7, 2018 at 4:54 AM Lee <[email protected]> wrote:
>
> After I added the pressure correction, the density of the cg system is very 
> close to the full-atomic system. Thanks for your advise. But when I use these 
> final potential table to do the tensile simulation for cg system, the system 
> is unstable. And the stress-strain curve is extrmely terrible. I saw someone 
> abtained a good stress-strain curve at 
> https://groups.google.com/forum/#!msg/votca/Jxsdz6v9QKw/OUVfYan8CwAJ . So I 
> want to know how could I get a good stress-strain curve with these potential 
> table? Or there still need some post process for these table?

That is magic of coarse-graining, if you parameterize a model on RDF
and pressure, it isn't obvious that the model will reproduce the
stress-strain curve. Maybe Frank knows some details and can comment
here.

Christoph
>
> 在 2018年12月3日星期一 UTC+8下午10:58:40,Christoph Junghans写道:
>>
>> On Mon, Dec 3, 2018 at 3:51 AM Lee <[email protected]> wrote:
>> >
>> >        Yes, you are right. I missed a important item, pressure correction. 
>> > But when I add pressure into the <post_update>, the error occurred 
>> > "Pressure correction for lammps is not implemented yet". Does the pressure 
>> > correction need to be implemented additionally? And how to implement it?
>>
>> Well it just means we haven't added support for pressure correction
>> when using lammps in that version.
>> However, it has been added here https://github.com/votca/csg/pull/201,
>> so either patch that in or use the development version of votca
>> instead (see 
>> https://github.com/votca/votca/blob/master/share/doc/INSTALL.md#general-source-installation-instructions.)
>>
>> Christoph
>>
>> >       Thanks
>> >
>> > 在 2018年12月3日星期一 UTC+8上午10:48:57,Christoph Junghans写道:
>> >>
>> >> On Sun, Dec 2, 2018 at 6:40 PM Lee <[email protected]> wrote:
>> >> >
>> >> > By checking the convergence value of interaction, I found that it was 
>> >> > stabilized above 1. When I use these potential table to do the cg 
>> >> > simulation, the density of cg system is half of that the corresponding 
>> >> > atomic system. So I think the nonbond interaction is still immature. 
>> >> > How to reach a lower convergence number? The rdf and the convergence 
>> >> > number of C-C are attched.
>> >>
>> >> Run longer iterations, finer binsize, in general everything which
>> >> increases the statistics helps.
>> >>
>> >> On the other hand, your RDF conversion looks pretty good already,
>> >> don't let this one number guide you, you need to test the
>> >> coarse-grained model, too.
>> >>
>> >> Christoph
>> >> >
>> >> > 在 2018年12月1日星期六 UTC+8下午9:44:34,Christoph Junghans写道:
>> >> >>
>> >> >> On Fri, Nov 30, 2018 at 8:00 PM Lee <[email protected]> wrote:
>> >> >> >
>> >> >> >       OK, thanks! I have increased the bin size and the distribution 
>> >> >> > seems to be smoothed.
>> >> >> >       In some paper, the IBI process is started from bond and then 
>> >> >> > angle, the nonbonded potential is finished at last. When doing ibi 
>> >> >> > for bond and angle, the pair interaction is turned off. The chains 
>> >> >> > are pushed apart to remove close contacts by slowly turning on a 
>> >> >> > soft, purely repulsive potential as you said before. But I couldn't 
>> >> >> > find the command in lammps.
>> >> >> That might be a question for the lammps mailing list!
>> >> >>
>> >> >> >       Another question, how could I output the value of convergence 
>> >> >> > for every iterative step?
>> >> >> The convergence numbers are stores in a files for each interaction
>> >> >> called <NAME>.conv and the sum is printed in the log files, so you can
>> >> >> do:
>> >> >> $ grep "Convergence sum" inverse.log
>> >> >>
>> >> >> This of course assumes you enabled the convergence check feature (with
>> >> >> setting cg.inverse.convergence_check.type to "default")
>> >> >>
>> >> >> Christoph
>> >> >> >
>> >> >> > 在 2018年11月30日星期五 UTC+8下午11:24:33,Christoph Junghans写道:
>> >> >> >>
>> >> >> >>
>> >> >> >>
>> >> >> >> On Fri, Nov 30, 2018 at 01:05 Lee <[email protected]> wrote:
>> >> >> >>>
>> >> >> >>> In votca, the smoothing process works for potential. Is there any 
>> >> >> >>> smoothing process for new distribution? And what's the command?
>> >> >> >>
>> >> >> >> No, but it would be hard to add!
>> >> >> >>
>> >> >> >> Also increasing the bin size naturally does smoothing!
>> >> >> >>
>> >> >> >> Christoph
>> >> >> >>>
>> >> >> >>>
>> >> >> >>>
>> >> >> >>> 在 2018年11月21日星期三 UTC+8下午9:03:19,Christoph Junghans写道:
>> >> >> >>>>
>> >> >> >>>> On Tue, Nov 20, 2018 at 6:44 PM Lee <[email protected]> wrote:
>> >> >> >>>> >
>> >> >> >>>> > The expression of boltzmann inversion is V=-kBTln(P). And the 
>> >> >> >>>> > distribution P is related to the scale of the x-coordinate. The 
>> >> >> >>>> > plot of bond distribution with different units are attached. In 
>> >> >> >>>> > votca, all the processes including calculating distributions 
>> >> >> >>>> > and boltzmann inversion are finished with units nm. So can I 
>> >> >> >>>> > say that the obtained potential table used in lammps is 
>> >> >> >>>> > converted by V=-kBTln(P) with the length units nm? So in 
>> >> >> >>>> > lammps, the dynamic simulation is finished with length units 
>> >> >> >>>> > angstroms but with the potential corresponding to units nm.
>> >> >> >>>>
>> >> >> >>>> Well, V(x)= -kBTln(P(x)) and x can be a distance or an angle etc. 
>> >> >> >>>> V
>> >> >> >>>> and P are always parameterized by the same variable in its units. 
>> >> >> >>>> Also
>> >> >> >>>> P(x) is a distribution and hence is unit-less, plus the 
>> >> >> >>>> normalization
>> >> >> >>>> of the distribution doesn't matter much as ln(a*P)=ln a + ln P and
>> >> >> >>>> hence only leads to an irrelevant offset in the potential and 
>> >> >> >>>> doesn't
>> >> >> >>>> matter to the forces.
>> >> >> >>>>
>> >> >> >>>> Christoph
>> >> >> >>>>
>> >> >> >>>> >
>> >> >> >>>> > 在 2018年11月20日星期二 UTC+8下午11:43:59,Christoph Junghans写道:
>> >> >> >>>> >>
>> >> >> >>>> >> On Tue, Nov 20, 2018 at 2:04 AM Lee <[email protected]> 
>> >> >> >>>> >> wrote:
>> >> >> >>>> >> >
>> >> >> >>>> >> >     I have another question. If my units command is real in 
>> >> >> >>>> >> > lammps which the units of distance and energy are angstroms 
>> >> >> >>>> >> > and Kcal/mole respectively, what shoud I change in the 
>> >> >> >>>> >> > setting file in order to get the potential table with right 
>> >> >> >>>> >> > units? Now, the bond and angle potential of the CG system 
>> >> >> >>>> >> > are much lower than the corresponding atomic system.
>> >> >> >>>> >>
>> >> >> >>>> >> Usually VOTCA calculated things in Gromacs units (so nm, 
>> >> >> >>>> >> kJ/mol etc.),
>> >> >> >>>> >> but if you only calculate RDFs you don't need to change 
>> >> >> >>>> >> anything as
>> >> >> >>>> >> input and output are both in nm and hence there is no scaling
>> >> >> >>>> >> involved. So this will work for angstroms as well. 
>> >> >> >>>> >> Additionally, you
>> >> >> >>>> >> need to make sure that kBT is in the right unit in the 
>> >> >> >>>> >> settings file.
>> >> >> >>>> >>
>> >> >> >>>> >> Christoph
>> >> >> >>>> >> >     Thanks a lot.
>> >> >> >>>> >> >
>> >> >> >>>> >> > 在 2018年11月20日星期二 UTC+8上午5:52:29,Christoph Junghans写道:
>> >> >> >>>> >> >>
>> >> >> >>>> >> >> On Mon, Nov 19, 2018 at 8:51 AM Christoph Junghans 
>> >> >> >>>> >> >> <[email protected]> wrote:
>> >> >> >>>> >> >> >
>> >> >> >>>> >> >> > On Sun, Nov 18, 2018 at 8:31 PM Lee <[email protected]> 
>> >> >> >>>> >> >> > wrote:
>> >> >> >>>> >> >> > >
>> >> >> >>>> >> >> > > For the dynamic simulations finished with lammps, 
>> >> >> >>>> >> >> > > should I set the exclusions? If excluding non-bonded 
>> >> >> >>>> >> >> > > interactions between atoms that are no further than 3 
>> >> >> >>>> >> >> > > bonds away, does it need to excluding these atoms when 
>> >> >> >>>> >> >> > > statistical target rdf distributon?
>> >> >> >>>> >> >> > >
>> >> >> >>>> >> >> > Yes, for LAMMPS you will most likely need to create rdf 
>> >> >> >>>> >> >> > exclusion manually.
>> >> >> >>>> >> >> >
>> >> >> >>>> >> >> > You can check, what exclusion VOTCA see by running:
>> >> >> >>>> >> >> > $ csg_dump --top <your_topology_file> --excl
>> >> >> >>>> >> >> >
>> >> >> >>>> >> >> > For advanced topology handling see, section 3.3 of the 
>> >> >> >>>> >> >> > manual,
>> >> >> >>>> >> >> > http://doc.votca.org/manual.pdf
>> >> >> >>>> >> >> Also Joshua might be able to say something about the new 
>> >> >> >>>> >> >> LAMMPS
>> >> >> >>>> >> >> topology reader in csg and how exclusions are incorporated 
>> >> >> >>>> >> >> there.
>> >> >> >>>> >> >>
>> >> >> >>>> >> >> Christoph
>> >> >> >>>> >> >> >
>> >> >> >>>> >> >> > Christoph
>> >> >> >>>> >> >> > > --
>> >> >> >>>> >> >> > > You received this message because you are subscribed to 
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>> >> >> >>>> >> >> >
>> >> >> >>>> >> >> >
>> >> >> >>>> >> >> >
>> >> >> >>>> >> >> > --
>> >> >> >>>> >> >> > Christoph Junghans
>> >> >> >>>> >> >> > Web: http://www.compphys.de
>> >> >> >>>> >> >>
>> >> >> >>>> >> >>
>> >> >> >>>> >> >>
>> >> >> >>>> >> >> --
>> >> >> >>>> >> >> 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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>> >> >> >> --
>> >> >> >> 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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>>
>>
>> --
>> Christoph Junghans
>> Web: http://www.compphys.de
>
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