[CPMD-list] Bizzare shapes of CUBEFILE ORBITALS

[Eung-Gun Kim]

Dear Axel,

Thanks very much for responding to my message.

As I keep only one compiled cpmd code at a time and use a single computational
resource, it is highly unlikely to have different grids for the computation and
analysis runs.

I just tried RHOOUT BANDS with negative indices on the same system and
encountered the following warning/error message:

   "WRITING OUT COMPLEX WAVFUNCTIONS (I.E. KPOINTS) NOTIMPLEMENTED"

So all this points to what you suspected is the source of the problem.  Would
you suggest any other workarounds?

Regards,

EG Kim


Quoting Axel Kohlmeyer <axel.kohlmeyer at theochem.ruhr-uni-bochum.de>:

>
> On Fri, 24 Jun 2005, Eung-Gun Kim wrote:
>
> EK> Dear List Subscribers,
>
>
> EK> I have observed some bizzare behavior when using "&PROP CUBEFILE
> EK> ORBITALS."  It can be summarized as follows:
> EK>
> EK>   1) Molecular orbitals, whether filled or unfilled, have unphysical
> shapes,
> EK>      which include long, pointed spears.
>
> that usually means, that the data was not sorted properly,
> you are mixing two datasets or have a different grid when
> generating and when plotting the data.
>
> EK>
> EK>   2) Even when the orbital shape looks "physical," ghost orbitals appear
> in
> EK>      empty space.  These ghosts look like replicas of the real ones.
> However,
> EK>      they are not something CUBECENTER can fix.
>
> again. can have the same reason, this time only the offset
> is commensurate with the grid.
>
> EK>   3) No matter how strange the orbitals are, the electron density as seen
> in
> EK>      the RHO_TOT.cube file looks just fine.  Energies (including the
> EK>      electronic band structure) are also fine.
> EK>
> EK>   4) Although my sampling may not be thorough, this happens when the
> orbitals
> EK>      are extracted from a k-point calculation.  (The way I extract
> orbitals at
> EK>      a particular k point is as follows: 1) perform optimization using
> EK>      KPOINTS MONKHORST-PACK; 2) perform 1 cycle of LANCZOS DIAGO on the
> EK>      optimized electron denstity using KPOINTS and the coordinates of
> EK>      a k point of interest, 0 0 0 for the gamma point, for instance; and
> EK>      3) perform a &PROP calculation.)
>
> hmmm. at least for the density there is a comment, that the CUBEFILE
> keyword was not tested at all for k-points. i'd assume, that the
> same is true for orbitals. note, that for KPOINTS you have a complex
> wavefunction, whereas for gamma point calculations it is real, and thus
> needing only have the storage. that may explain your strange cube files.
>
> EK>   4) It does *not* happen all the time.
> EK>
> EK>   5) I tested it with both v3.9.1 and v3.9.2, and obtained the same
> result.
> EK>
> EK> What I've seen so far suggests that the bug--if there exists one--may be
> in the
> EK> cubefile-generating routine for ORBITALS.  Would there be a workaround?
>
>
> you can try to use RHOOUT BANDS with the _negative_ numbers of the
> respective orbitals. from that you'll get a bunch of WAVEFUNCTION.*
> files, for the states in question that you can convert to the
> respective cubefiles with cpmd2cube.
>
> with the numerous improvements to cpmd2cube over the
> last years, i'd generally prefer using cpmd2cube. e.g.
> for orbitals using the -trim flag can save an enourmous
> amount of storage (on disk and in memory when visualizing
> them), provided the cube'd data is not very distributed.
>
> best regards,
> 	axel.
>
> EK>
> EK> Thanks very much for reading.
> EK>
> EK> Regards,
> EK>
> EK> EG Kim
> EK> _______________________________________________
> EK> CPMD-list mailing list
> EK> CPMD-list at cpmd.org
> EK> http://cpmd.org/mailman/listinfo/cpmd-list
> EK>
> EK>
>
> --
>
> =======================================================================
> Dr. Axel Kohlmeyer   e-mail: axel.kohlmeyer at theochem.ruhr-uni-bochum.de
> Lehrstuhl fuer Theoretische Chemie          Phone: ++49 (0)234/32-26673
> Ruhr-Universitaet Bochum - NC 03/53         Fax:   ++49 (0)234/32-14045
> D-44780 Bochum  http://www.theochem.ruhr-uni-bochum.de/~axel.kohlmeyer/
> =======================================================================
> If you make something idiot-proof, the universe creates a better idiot.
>
>