[CPMD-list] Energy components in PIMD

[Axel Kohlmeyer]

On Thu, 15 May 2008, ukasz Walewski wrote:

LW> > LW> > BTW: based on its "spectrum" i have changed coupling frequency
LW> > LW> > for the N-H chains to 2500 cm-1, if you look at the second 
LW> > LW> > attached graph this seems a much more reasonable choice as it
LW> > LW> 
LW> > LW> What do you call "spectrum" in this case ? - with FFT(EKINC) I get
LW> > LW> something different...
LW> > 
LW> > this was run though the fourier.x code and "temperature corrected".
LW> 
LW> Hmm... fourier.x does not seem to be bundled with CPMD (nor CP2K). Where
LW> can I find it (Google doesn't know) ?

it is supposed to be in the contrib section of the www.cpmd.org
download area, but it looks like it never made it there... :-(

it should be available from the download area of my (old) bochum
pages at http://www.theochem.rub.de/~axel.kohlmeyer/cpmd-tutor/files/

if you have a recent version of VMD installed you can also use
the (bundled) specden plugin. the specden command is basically 
a tcl version of what fourier.x does. it is not (yet) well documented,
so to use it conveniently you need to do some tcl scripting magic
(which you could "steal" from the irspecgui plugin).

LW> > extrapolation and some other tricks (that are not yet in 3.11.)
LW> > i get very good energy conservation with the attached input,
LW> 
LW> The input I received (as well as the previous one in this thread)
LW> contains some lines at the beginning of the file that do not belong to
LW> any &SECTION ... &END section. Is it intentional ?

they are in there because i am basically a lazy person,
and favor copying lines of text around to typing them.
anything outside a section is completely ignored. 
i prefer this method to "disable" command over changing 
the first character to lower case, which many people do, 
as this does not produce any spurious error messages and
does not accidentally trigger similar keywords.

LW> 
LW> > cheers,
LW> >    axel.
LW> > 
LW> > p.s.: after going through so many tests and checking out so many 
LW> > details. what do you think about summarizing your experiences and
LW> > adding it to the CPMD manual as a guide for other CPMD users?
LW> 
LW> I would avoid making any promises here but I will keep this in mind.

it shouldn't be too difficult. you can start by downloading the 
mailing list archive and editing that text. this is how the whole 
questions and answers section in the manual came to be, for example...

cheers,
   axel.


LW> 
LW> Best regards,
LW> Lukasz
LW> 

-- 
=======================================================================
Axel Kohlmeyer   akohlmey at cmm.chem.upenn.edu   http://www.cmm.upenn.edu
   Center for Molecular Modeling   --   University of Pennsylvania
Department of Chemistry, 231 S.34th Street, Philadelphia, PA 19104-6323
tel: 1-215-898-1582,  fax: 1-215-573-6233,  office-tel: 1-215-898-5425
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If you make something idiot-proof, the universe creates a better idiot.