[Wien] LSDA+U on Yb compounds

[Zsolt Rak]

Hi Stefaan,

Thank you for the prompt reply. I followed your instructions to find out the 
4f occupancy. Here are my results for YbAl3:

:PCS001: PARTIAL CHARGES SPHERE =  1 S,P,D,F
:QTL001: 1.0705 2.9374 0.3427 6.7838  -up
:QTL001: 1.0705 2.9374 0.3427 6.7838  -dn

:TRA001:  TRACE of UPUP MATRIX=   6.78385   0.00000
:TRA001:  TRACE of UPDN MATRIX=   0.00000   0.00000
:TRA001:  TRACE of DNDN MATRIX=   6.78385   0.00000

FERMI ENERGY=   0.54730 -from .outputtup
 0.54800    ...     0.94   6.7828 -up
 0.54800    ...     0.94   6.7828 -dn

 It seems that there are about 13.5 -13.6 electrons in  the 4f level, 
thirteen of which should be below Femi energy and one partly occupied level 
should be "pinned" at the Fermi level (correct me if I'm wrong!)- but all I 
am geting are the filled states. I also want to mention that LSDA+U 
calculation on a Ce compound gave one occupied state below fermi energy 
(large,visible peak) and the rest of  the unoccupies states above EF.
It is also puzzeling to me that there is no difference between -up and -dn 
states.
How can I "force" a divalent or trivalent solution?

Thanks again,
Zsolt




----- Original Message ----- 
From: "Stefaan Cottenier" <Stefaan.Cottenier at fys.kuleuven.be>
To: <wien at zeus.theochem.tuwien.ac.at>
Sent: Wednesday, July 26, 2006 11:02 AM
Subject: Re: [Wien] LSDA+U on Yb compounds


>
> Can you verify explicitely whether you have 13 or 14 4f-electrons? Do
> this by looking at the partial charges for f (:QTL), or by summing the
> diagonal elements of the up and dn density matrices, or by looking at
> the value of the integrated partial f-dos at the fermi level in
> case.outputt (and preferably do it by all three methods, they should
> give the same answer).
>
> If you really have 14 electrons, you might have ended up with divalent
> Yb. If you have 13 electrons, perhaps your unoccupied state is diffuse
> and not at first sight recognizable as a peak.
>
> Stefaan
>
>> I am performing LSDA+U calculations on a series of Yb compounds in which 
>> the
>> valence of Yb is close to 3+. I was expecting to get a splitting between 
>> the
>> occupied and unoccupied 4f states, but my DOS only shows the occupied
>> 4f-states located well below the Fermi level, without any empty 
>> 4f-states.
>> I'm doing the following:
>>
>> runsp_lapw  -cc 0.001;
>> runsp_lapw -so -cc 0.001;
>> runsp_lapw -so -orb -cc 0.001.
>>
>> for DOS I do:
>> x lapw1 -orb -up/dn
>> x lapwso -up -orb
>> x lapw2 -qtl -so -up/dn.
>>
>>
>> It also seems that with LSDA+U there is no difference between -up and -dn
>> states. (and I'm not using runsp_c_lapw).
>> Is there any wien2k user who was able to observe the empty 4f states of 
>> Yb,
>> located at or above Fermi level?
>>
>> Thanks,
>> Zsolt Rak
>>
>> _______________________________________________
>> Wien mailing list
>> Wien at zeus.theochem.tuwien.ac.at
>> http://zeus.theochem.tuwien.ac.at/mailman/listinfo/wien
>>
>>
>
>
>
> -- 
> Stefaan Cottenier
> Instituut voor Kern- en Stralingsfysica
> K.U.Leuven
> Celestijnenlaan 200 D
> B-3001 Leuven (Belgium)
>
> tel: + 32 16 32 71 45
> fax: + 32 16 32 79 85
> e-mail: stefaan.cottenier at fys.kuleuven.be
>
>
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