[Wien] Tb metal

[Peter Blaha]

A few more comments in addition to what L.Marks said:

a) In this paper they say: The magnetization is along the b-axis, i.e. 
(1-100).
In WIEN2k we use a different convention, where the hexagonal b axis and 
the carth. y axis coincides (and not the a and carth. x axis). I thus 
believe it should be the (010) direction !

b) As mentioned before, with localized 4f (or sometimes 3d) states it is 
easily possible to obtain several metastable minima as solution of an 
unbiased scf cycle when using GGA+U. It is therefore important (but not 
always sufficient) to run a sequence:

runsp -so

and only afterwards:
x lapwdm -so -up/dn
runsp -so -orb

If you still do not get the desired solution, you can try and manually 
reoccupy the 4f orbitals in case.dmatup/dn.
Presumably, Tb has a full 4f spin-up shell, but only one spin-dn 
electron. This gives a spin moment of 6, and in order to get an orbital 
moment of 3, an m=3 state must be occupied in spin-dn.
Presumably your spin-dn density matrix with M_orb=1.5 looks quite different.

You can then also compare total energies of the different solutions ..



On 12/05/2016 07:10 PM, Guo-ping Zhang wrote:
> Dear Prof. Blaba and Wien2k developers,
>
> Thank you very much for your prior help.
>
> Recently, I was testing whether Wien2k can compute Tb metal's spin and
> orbital  moments correctly, but unsuccessful. I follow the paper by
> Dobrich et al. PRB 76, 035123 (2007). The correct spin moment should be
> around 6 uB and orbital 3 uB, but Wien gave spin moment of 11.72562 uB/2
> which is close to 6 uB (which is OK), and the orbital moment of 1.43494
> uB (:ORB001), which is too small. My RKmax is 9.52. I include 4f in the
> valence, (case.in1: 3    0.30      0.005 CONT 1 ). I also checked my
> case.inst. It looks also fine.
> Tb
> Xe 4
> 4, 3,3.0  N
> 4, 3,1.0  N
> 4,-4,4.0  N
> 4,-4,0.0  N
> 5, 2,1.0  N
> 5, 2,0.0  N
> 6,-1,1.0  N
> 6,-1,1.0  N
> ****
> ****         END of input (instgen_lapw)
>
> In case.scf the number of electrons (:NOE) is consistently 38. This is
> also correct. What is even strange is that the results do not change by
> adding +U option or not.
>
> +U results
> :ORB001:  ORBITAL MOMENT:  0.72713 -1.25942  0.00000 PROJECTION ON M
> 1.45428
> :MMTOT:  SPIN MAGNETIC MOMENT IN CELL     =   11.65626
>
> U=0 results
> :ORB001:  ORBITAL MOMENT:  0.71746 -1.24270  0.00000 PROJECTION ON M
> 1.43494
> :MMTOT:  SPIN MAGNETIC MOMENT IN CELL     =   11.72562
>
>
> I have attached my structure file in case you want to test it youself.
>
> I can not figure out why wien did this all incorrect.
>
> Any help is greatly appreciated.
>
> Best regards,
>
> Guoping
>
>
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-- 

                                       P.Blaha
--------------------------------------------------------------------------
Peter BLAHA, Inst.f. Materials Chemistry, TU Vienna, A-1060 Vienna
Phone: +43-1-58801-165300             FAX: +43-1-58801-165982
Email: blaha at theochem.tuwien.ac.at    WIEN2k: http://www.wien2k.at
WWW:   http://www.imc.tuwien.ac.at/TC_Blaha
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