[Wien] inversion vs time reversal

[Peter Blaha]

time inversion symmetry is used in WIEN2k only for the generation of the 
k-mesh when "inversion" is not present (and it is not a magnetic case 
with spin-orbit). In that case we use the fact that 
epsilon(k)=epsilon(-k) and "add" the (-1,-1,-1) diagonal matrix to the 
symmetry operations reducing the full BZ mesh to the IBZ.

Everywhere else, only "inversion" is used (if present), which makes 
wavefunctions "real" and one can use lapw1 instead of lapw1c.

If you try to run Si with (0,0,0) and (1/4,1/4,1/4), you must "trick" 
the initialization procedure, because WIEN2k will normally not allow it, 
because it requires an 4 times larger computational effort.

On 2/6/20 6:26 AM, 姜若诗 wrote:
> Dear professors,
> 
> Do you know how to deal with the inversion symmetry and time reversal 
> symmetry in wien2k, how do you make them different ?
> 
> For example, if the positions of two atoms Si is in (0.125 0.125 0.125) 
> and (0.875 0.875 0.875), the system has inversion and time reversal 
> symmetry, then the point group symmetry matrix has number 48.
> 
> But if the positions are (0 0 0) and (0.25 0.25 0.25), the system 
> doesn’t has the inversion symmetry, with time reversal symmetry left, 
> will the symmetry matrix reduce to number 24, or also number 48?
> 
> In a word, what my question is :  Does the symmetry matrix  (-1 0 0, 0 
> -1 0, 0 0 -1)  show not only the inversion symmetry , but also time 
> reversal symmetry in a system?
> 
> Looking forward to your reply
> 
> Regards,
> 
> Jasmine.
> 
> 
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-- 

                                       P.Blaha
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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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