Thanks Christoph and Victor.

Before I do what you have suggested, I do not know yet 100% how to get
both bonded and non-bonded potentials in VOTCA "correctly".

1. For instance, how do you obtain the table.pot file?
This file is needed to start the following sequence of commands:

csg_sample --in table.pot --out table_resample.pot --grid min:step:max
csg_call table extrapolate table_resample.pot table_extrapolate.pot
csg_call --options table.xml convert_potential gromacs
table_extrapolate.pot table.xvg

2. Similarly, how do I obtain the table.pot for both the bonded and
angle potentials
which I will resample, extrapolate and later convert to table_b1.xvg
and table_a1.xvg?

Is the way of obtaining the target non-bonded potentials for the IBI
method through force matching (csg_fmatch)
or are the potentials only supposed to be derived using csg_stat and/
or csg_boltzmann?

Perhaps a step-by-step explanation will help me to reproduce your
hexane tutorial and serve to help the other new VOTCA users as well.

Thanks a lot.

Tinashe






On Jan 18, 9:36 pm, Christoph Junghans <[email protected]> wrote:
> Hi Tinashe,
>
> welcome!
>
> Am 18. Januar 2012 07:18 schrieb Tinashe <[email protected]>:> - the 
> min/max/step values for force matching i get from the
> > distribution functions, that it samples a valid interval, and the
> > number of bins is not too high, otherwise might become slow
> > - the table_a1*.xvg are usually generated using csg_boltzmann, there
> > is a section in the manual. You can convert the votca potential files
> > to gromacs using csg_call. I have to lookup the correct command, but
> > christoph might answer on googlrgroups.
>
> See section 4.2 of the manual:
> <https://votca.googlecode.com/files/votca-csg-manual-1.2.2.pdf>
>
> But basically once you have the potential in Votca format, it boils
> down to the following:
> -create a simple settings xml file (table.xml):
> <cg>
> <inverse>
> <gromacs>
> <pot_max>1e8</pot_max>
> <table_end>8.0</table_end>
> <table_bins>0.002</table_bins>
> </gromacs>
> </inverse>
> </cg>
> and run
> $csg_call --ia-type TYPE --options table.xml convert_potential gromacs \
> table_extrapolate.pot table.xvg
> where  type can be non-bonded, bonded, angle, dihedral.
>
> Note, that in the current development version we renamed "bonded" to "bond"!
>
> Cheers,
>
> Christoph
>
>
>
>
>
> > - renaming te distribution function and use it as target is the proper
> > way to do
> > - you can make a few optimizations in the grompp, e.g. if you don't
> > have charge in the cg model, use cut-off as estatic method. this will
> > disable the fft from pme.
>
> > Best,
> > Victor
>
> >> Dear Victor,
>
> >> Firstly, thanks a lot, your suggestions were on the mark.
>
> >> At first, I ran the following command:
> >> csg_stat --top topol.tpr --trj traj.trr --cg hexane.xml --nt 3 --options
> >> fmatch.xml
> >> and then renamed the files from *.dist.new to *.dist.tgt to use together
> >> with the settings file. Is this the correct way to things?
>
> >> How are the following files meant to be created: table.xvg table_a1.xvg
> >> table_b1.xvg
> >> Where does one get the numbers in the settings.xml and fmatch.xml? I have
> >> simply used numbers from VOTCA tutorials?
> >> It appears that I can still use the same grommp file as the one I used for
> >> atomistic simulations, is this so?
>
> >> Kind regards,
> >> Tinashe
>
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> --
> Christoph Junghans
> Web:http://www.compphys.de- Hide quoted text -
>
> - Show quoted text -

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