[CPMD-list] constraints...

[Axel Kohlmeyer]

On Mon, 26 Nov 2007, Jaakko Saukkoriipi wrote:

JS> Hi!

jaakko,

JS> I have been calculating energy barriers for certain chemical reactions
JS> using CPMD. This I have done simulating the system in different fixed
JS> positions. Fixed bond distances are put to the input-file in angstroms. So
JS> my question is: What is the unit of the Force that is given to the
JS> CONSTRAINT file during simulation? Is it a.u./a.u. or a.u./å? I haven't
JS> found the answer from the manual, so I would be highly appreciated if
JS> someone can help me with this small problem.

internally, _everything_ in CPMD is in hartree atomic units
which is also true for most of the outputs, unless the format
assumes something else (e.g. .xyz files or .dcd files).

a strong hint should be that the constraint value (e.g.
the bond length constraint) is written out in a.u.

the ANGSTROM flag triggers a (sometimes incomplete)
series of conversions where input parameters are converted
to atomic units. if i remember correctly, ANGSTROM initially
only applied to coordinates and was then over time expanded
to other parameters as well.


cheers,
   axel.

JS> 
JS> Regards, Jaakko Saukkoriipi
JS> 
JS> ¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤
JS>                           M.Sc.  Jaakko Saukkoriipi
JS> 
JS>         University of Oulu                      Rysätie 6 A 4
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JS> 
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-- 
=======================================================================
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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