[CPMD-list] Geometry optimization and misrepresentation of the x-ray data...

[Axel Kohlmeyer]

On Fri, 25 Apr 2008, Pedro Nuno Simões wrote:

PNS> Dear Axel

dear pedro,

PNS> I accept your criticism. But as I firstly said, I am a beginner 
PNS> both in CPMD code and CPMD mailing list, and I assume my lack of 
PNS> experience in the field. Obviously, I had no intention to make 

i understand that, but that is exactly why it needs to be said
repeatedly and why the CPMD manual _does_ contain references 
to web pages that _explain_ how to report problems. 

PNS> things difficult. The complete


PNS> input is attached.

ok, so i just ran the minimal test:

WAVEFUNCTION OPTIMIZATION, 
MAXSTEP 1, CUTOFF 10

added RHOOUT to the &CPMD section
and cpmd2cubed the resulting DENSITY file
to be viewed in VMD (including periodicity.

=> your system has "holes" so it looks like
there is an additional symmetry (inversion?)
in your CIF file that you have not replicated?

also, it looks like you will have to think about
how much your structure is determined by dispersion
interactions, and how you are going to deal with
it. as current GGA-DFT functionals tend to largely
underrepresent those interactions.

cheers,
   axel.

-- 
=======================================================================
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.