[Wien] Fermi surface not 4 fold symmetric for a cubic material with space group Pm3m

[Peter Blaha]

One needs more information.

Just a few possibilities:

I do NOT understand how you did a "nonmagnetic" GGA+U calculation. It 
works ONLY in spinpolarized mode (but of course you can restrict the 
spin to zero)

Make sure that you do NOT use a   shifted k-mesh   for FS calculation.

And make sure you create the k-mesh ALWAYS with the   -so  switch

Of course, after initso, the symmetry MUST BE REDUCED (no longer Pm3m 
and 48 symmetry operations). The exact symmetry depends on the direction 
of magnetization.

Regards

On 11/5/18 8:53 AM, Anup Shakya wrote:
> Dear All,
> I have done non-magnetic GGA+SOC+U calculations with U and J for a 
> material containing rare earth element. Without SOC and U the Fermi 
> surface is 4 fold symmetric but when I performed GGA+SOC+U calculations 
> the Fermi surface is not 4 fold symmetric. Before applying SOC the 
> position of the atoms were as follows:
> Atom X Mult =1  0.0      0.0       0.0
> Atom Y Mult 6  0.207   0.5      0.5
> After SOC the a,b,c values and the symmetry i.e, Pm3m is the same as 
> before but now the Y positions has split into two non-equivalent atoms 
> as shown below.
> Atom Y 2 Mult 4 0.207   0.5  0.5
> Atom Y 3 Mult 2 0.5      0.5   0.207.
> The position and the multiplicity of X atom is unchanged. I think 
> probably because of SOC the equivalent atoms have changed into 
> non-equivalent atoms and led to the anisotropy in the band structure 
> along the G-X and X-G direction and also 4 fold symmetry is not there in 
> the Fermi surface calculations. But if I want to compare the obtained 
> band structure or the Fermi surface with the ARPES results then it 
> doesn't make sense because the Fermi surface should be 4 fold symmetric. 
> I do not know what to do. If you need any more information then please 
> let me know. Please provide some suggestions as to preserve the 4 fold 
> symmetry along with GGA+SOC+U calculations. Any suggestion would be very 
> much valuable for me.
> 
> Sincerely,
> Anup Pradhan Sakhya,
> TIFR, India
> 
> 
> 
> 
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                                       P.Blaha
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Peter BLAHA, Inst.f. Materials Chemistry, TU Vienna, A-1060 Vienna
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