[Wien] Improving vacuum basis set

[Torsten Andersen]

Dear Mr. Marks,

that it appears at z=0.5 is suspicious to me. I would suggest that you 
make your supercell larger (my experience says 12-16 vacuum "layers" 
plus epsilon), and that you change the cell size in the "vacuum" 
direction(s) to a non-integer multiple of the lattice parameter(s). 
Then, as a third option, increase GMAX and/or RMT*kmax.

Alternatively, there is a film-LAPW code from Jülich which matches the 
vacuum with evanescent waves, as far as I remember.

Best regards,
Torsten Andersen.

Laurence Marks wrote:
> Not in fact an atom, rather the electron density. I'm getting some
> relatively flat, small density (~1e-4 via lapw5/rhoplot) far from the
> surface, which appears to be stabilized by it's exchange-correllation
> energy (vxc potential around -0.1 at z=0.5). I'm not sure if it's
> real, or whether the basis-set for this type of density might not be
> poor.
> 
> On 10/23/06, georg at chem.au.dk <georg at chem.au.dk> wrote:
> 
>>Do you mean an atom some distance from (weakly bonded to) the surface?
>>
>>One thing is that WIEN sets the linearization energy to 0.30 because the
>>fermienergy is "usually" around 0.5 Ry in densely packed solids, so 0.3Ry can
>>be expected to be somewhere in the valence bands.
>>
>>If you have an atom the upper most state will have a negative energy so often
>>the lineraization energy needs to be changed. As the bands are flat sometimes
>>the energies have to be set very precisely. Maybe the -in1new option can help
>>you.
>>
>> Best wishes Georg
>>Quoting Laurence Marks <L-marks at northwestern.edu>:
>>
>>
>>>I am running in to some issues with electrons at some distance from a
>>>surface, and I suspect that I might not have the best basis set for
>>>these in a conventional calculation. I'm wondering if anyone has
>>>thought about this problem and come up with some ideas to try.
>>>
>>>--
>>>Laurence Marks
>>>Department of Materials Science and Engineering
>>>MSE Rm 2036 Cook Hall
>>>2220 N Campus Drive
>>>Northwestern University
>>>Evanston, IL 60208, USA
>>>Tel: (847) 491-3996 Fax: (847) 491-7820
>>>email: L-marks at northwestern dot edu
>>>http://www.numis.northwestern.edu
>>>_______________________________________________
>>>Wien mailing list
>>>Wien at zeus.theochem.tuwien.ac.at
>>>http://zeus.theochem.tuwien.ac.at/mailman/listinfo/wien
>>>
>>
>>
>>--
>>Georg Madsen
>>Department of Chemistry
>>Aarhus University
>>DK-8000 Århus C
>>Denmark
>>tlf (+45) 89423885
>>http://www.chem.au.dk/~webuorg/gm
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>>Wien mailing list
>>Wien at zeus.theochem.tuwien.ac.at
>>http://zeus.theochem.tuwien.ac.at/mailman/listinfo/wien
>>
> 
> 
> 

-- 
Dr. Torsten Andersen        TA-web: http://deep.at/myspace/
AG Hübner, Department of Physics, Kaiserslautern University
http://cmt.physik.uni-kl.de    http://www.physik.uni-kl.de/