[Wien] LSDA+U on Yb compounds

[Stefaan Cottenier]

All of these three methods give the charge within the muffin tin  
spere. Which sphere sizes are you using? I guess the 4f states are not  
completely confined within the spheres, and your 6.78 corresponds to 7  
electrons (a little bit of them being in the interstitial region). If  
that is true, then you have divalent Yb with 14 electrons.

I never did it, but you can try to force trivalency by putting 13  
electrons in the density matrices, converging with -orbc (density  
matrices fixed), then release it and converge again with -orb -- and  
now hoping that this solution will be kept. I'm curious whether that  
will work. Has anybody different suggestions?

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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>
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>



-- 
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


Disclaimer: http://www.kuleuven.be/cwis/email_disclaimer.htm