[Pw_forum] about U value determination in DFT+U calculation

[Gabriele Sclauzero]

Dear Jia Chen,

    do you really need to use this specific pseudopotential? It looks 
like it was built for specific purposes (XPS calculations) and has some 
non-standard features (in my opinion at least). Specifically, it has 
more wavefunctions than beta projectors and moreover the 3d channel is 
treated as local (I don't if and how this may affect transferability).
However the 3D wavefunction is present and has occupation greater than 
zero (contrary to the 4D wfc), so I can't see the reason why the code 
should give such result. I will have a look at it, but in the meanwhile 
I suggest you to try also one of the other PBE  PPs for Co which are 
present on the QE website.


GS

On 07/19/2010 11:13 PM, jia chen wrote:
> Dear Gabriele Sclauzero,
>
> Thank you so much for your help. I did an atomic calculation according 
> to your suggestion using that pseudo-potential. Sadly, the occupation 
> number is not correct.
> first step
> atom    1   Tr[ns(na)]=   7.0000000
> and after optimization
> atom    1   Tr[ns(na)]=   0.0748899
>
> The pseudo-potential I got from website of QE named 
> Co.pbe-sp-mt_gipaw.UPF 
> <http://www.pwscf.org/pseudo/1.3/UPF/Co.pbe-sp-mt_gipaw.UPF>
> and header of this pseudo-potential is copied below
> <PP_HEADER>
>     0                   Version Number
>    Co                   Element
>     NC                  Norm - Conserving pseudopotential
>      F                  Nonlinear Core Correction
>   SLA  PW   PBX  PBC    PBE  Exchange-Correlation functional
>     17.00000000000      Z valence
>   -287.58146877626      Total energy
>        0.000      0.000 Suggested cutoff for wfc and rho
>      2                  Max angular momentum component
>   1193                  Number of points in mesh
>      6    2             Number of Wavefunctions, Number of Projectors
>   Wavefunctions         nl  l   occ
>                         3S  0  2.00
>                         4S  0  0.00
>                         3P  1  6.00
>                         4P  1  0.00
>                         3D  2  7.00
>                         4D  2  0.00
> </PP_HEADER>
>    
> According to your post, I don't think it can be any problem, but 
> atomic calculation I did is not correct. Can you give me further help 
> about what can go wrong? I looked inside offset_atom_wfc.f90, but I 
> have no idea how to check if pw picks right atomic wavefunction.... 
> Can you give me some hints about that? Thank you so much!
>
> Bests
> -- 
> Jia Chen
>
> Dept of Chemistry
> Princeton University
> Princeton, NJ 08544
>
>
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>    


-- 

Gabriele Sclauzero, EPFL SB ITP CSEA
PH H2 462, Station 3, CH-1015 Lausanne

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