Wrapping cp2k

Matt obfis... at gmail.com
Sat May 5 19:00:11 CEST 2007


Hi Toon.  As Juerg mentioned, GEMC is already in the code (if you look
in cp2k/tests/MC/regests, you will find a couple input file examples),
and I have tested it for Fist/KG/QS (we've published simulations on QS
before, and I think we're in the process of publishing one on KG).  I
admit that the input structure is a little convoluted for GEMC at the
moment, and I apologize for that.  Please, if you have any questions
about how things work or need more information I would be happy to
respond.  Be warned that my email access will become sporadic after
next week as I'm moving to Africa, but I'll help you in any way I
can.  If you're familiar with GEMC, I hope there is enough
documentation about the keywords in the code that it won't be too
difficult to figure out.  I'm excited that there is someone else out
there who wants to use CP2K-MC.

In regards to your wrapper comment, we did initially debate that
question (easier to write the MC routines natively, or through an
interface).  In the end we decided to put everything directly into the
source into a style that resembles that used by the rest of the
developers, in hopes that maintainence would be easier.

               Cheers, Matt

On May 4, 1:13 pm, Toon <Toon.Ver... at gmail.com> wrote:
> Thanks for all the positive replies! Sorry for having ignored existing
> features. For GEMC, it will certainly be most wise to use the builtin
> features, but I'm still interested in the f77 interface anyway. I
> found a few examples in the tools directory.
>
> cheers,
>
> Toon
>
> On 4 mei, 18:47, Juerg Hutter <hut... at pci.uzh.ch> wrote:
>
> > Hi
>
> > it is implemented, see
>
> > MOTION%MC ENSEMBLE : PROGRAM (TRADITIONAL|GEMC_NVT|GEMC_NPT|VIRIAL)
>
> > GEMC = Gibbs Ensemble Monte Carlo
>
> > For published applications see
>
> >   McGrath MJ, Siepmann JI, Kuo IFW, et al.
> > Simulating fluid-phase equilibria of water from first principles
> > JOURNAL OF PHYSICAL CHEMISTRY A 110 (2): 640-646 JAN 19 2006
>
> >   McGrath MJ, Siepmann JI, Kuo IFW, et al.
> > Vapor-liquid equilibria of water from first principles: comparison of
> > density functionals and basis sets
> > MOLECULAR PHYSICS 104 (22-24): 3619-3626 NOV-DEC 2006
>
> > It should now work with most methods (Fist/KG/QS), but
> > Matt can certainly give you more information.
>
> > If you still want to use an external wrapper you can use
> > the F77 interface to CP2K by Fawzi.
>
> > best regards
>
> > Juerg
>
> > ----------------------------------------------------------
> > Juerg Hutter                   Phone : ++41 44 635 4491
> > Physical Chemistry Institute   FAX   : ++41 44 635 6838
> > University of Zurich           E-mail: hut... at pci.uzh.ch
> > Winterthurerstrasse 190
> > CH-8057 Zurich, Switzerland
> > ----------------------------------------------------------
>
> > On Fri, 4 May 2007, Toon wrote:
>
> > > Hi,
>
> > > I would be interested in using the Gibbs ensemble technique of
> > > Panagiotopoulus to study first order phase transitions with cp2k. I
> > > have no clear idea of what the mc capabilities in cp2k are, but as far
> > > as I can see, the Gibbs ensemble is not implemented. Instead of adding
> > > yet more lines of code that implement such a feature, I would like to
> > > consider another option.
>
> > > Would it be difficult to let cp2k read coordinates (, velocities, cell
> > > parameters, changes in connectivity, added molecules, removed
> > > molecules, ...) for each time step from the stdin, and let it
> > > calculate on the fly the corresponding energy, gradient, temperature,
> > > virial, pressure, ...? This would make it easy to move the md/mc part
> > > to an external program which would offer many advantages:
>
> > > * The external program does not have to be written in the most
> > > efficient way, because it is only doing a minor part of the
> > > computational job. It could be any high level scripting language with
> > > a good array support (e.g. python with numpy). This would hugely
> > > facilitate the implementation of complex MC/MD/Whatever schemes and it
> > > offers a flexibility that can never be obtained with any kind of input
> > > file syntax.
>
> > > * The external program could feed more than one cp2k program at the
> > > same time, which is particularly useful for the Gibbs ensemble
> > > technique.
>
> > > * Moving parts of cp2k (in this case the motion part) to a higher
> > > level language is in general good idea since the same algorithm in a
> > > higher level language counts less lines. (read: less bugs, easier to
> > > maintain, platform independent, no compiler misery.)
>
> > > The implementation should not modify anything to the existing code, it
> > > only adds a new RUN_TYPE. The external program could still call cp2k
> > > with a conventional input file, but with RUN_TYPE set to 'IO' or
> > > something similar. This should imply that cp2k reads the
> > > configurational changes from the input and writes the energy-related
> > > information to the output, with a well-defined and compact protocol.
> > > This protocol should somehow be flexible towards future extensions,
> > > without becoming a bottleneck.
>
> > > What do you think of this idea? To make things easier, you are invited
> > > to reply, quoting one of the following lines, followed by your
> > > comments:
>
> > > * Good idea, I'll implemented this right now.
> > > * Good idea, but do it yourselves. We would be happy to include your
> > > contributions in the main code once it works.
> > > * Good idea, but do it yourselves and it might take a very long time
> > > before this will be a part of cp2k.
> > > * Bad idea. :-(
>
> > > have a nice weekend,
>
> > > Toon




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