[Wien] irrep+soc could not write the parity eigenvalues for some bands in Bi2Se3.

[Bramhachari Khamari]

Dear wien2k users,

     In order to calculate the topological invariant Z2  for the system
having inversion symmetry, one needs to know the parity eigen values of the
bulk bands. To calculate the parity eiegenvalues of the material Bi2Se3, I
performed the "irrep+soc " calculation. Although I got the eigenvalues to
be atleast doubly degenerate, in some of the bands I could not get the
parity,  instead a ?? is written . Here is output at high symmetry point
Gamma.

bnd ndg  eigval     E         2C3         3C2           I
2IC3        3IC2
  1  2 -3.134698 2.00-0.00i  1.00-0.00i  0.00-0.00i  2.00-0.00i
1.00+0.00i  0.00-0.00i =G4+
  3  4 -3.134310 4.00+0.00i -1.00+0.00i  0.00+0.00i  4.00+0.00i -1.00-0.00i
-0.00-0.00i =G4+ + G5+ + G6+
  7  4 -3.132571 4.00-0.00i -1.00+0.00i -0.00+0.00i  4.00-0.00i -1.00-0.00i
-0.00-0.00i =G4+ + G5+ + G6+
 11  2 -3.131526 2.00+0.00i  1.00+0.00i  0.00-0.00i  2.00+0.00i
1.00-0.00i  0.00-0.00i =G4+
 13  2 -3.131510 2.00+0.00i  1.00-0.00i -0.00+0.00i -2.00+0.00i
-1.00-0.00i  0.00-0.00i =G4-
 15  4 -3.131454 4.00+0.00i -1.00+0.00i  0.00+0.00i  4.00+0.00i -1.00-0.00i
-0.00+0.00i =G4+ + G5+ + G6+
 19  4 -3.131391 4.00+0.00i -1.00+0.00i -0.00+0.00i -4.00-0.00i
1.00+0.00i  0.00+0.00i =G4- + G5- + G6-
 23  4 -3.130897 4.00+0.00i -1.00-0.00i  0.00-0.00i  4.00+0.00i -1.00+0.00i
-0.00+0.00i =G4+ + G5+ + G6+
 27  4 -3.130814 4.00-0.00i -1.00-0.00i  0.00+0.00i -4.00+0.00i
1.00-0.00i  0.00-0.00i =G4- + G5- + G6-
 31  2 -1.457486 2.00+0.00i -1.96-0.00i -0.00-0.00i  2.00-0.00i -1.96+0.00i
-0.00-0.00i ??
 33  2 -1.456647 2.00+0.00i  0.98+0.00i  0.00+0.00i  2.00+0.00i
0.98-0.00i  0.00+0.00i ??
 35  2 -1.456549 2.00-0.00i -1.95-0.00i -0.00-0.00i -2.00-0.00i  1.95-0.00i
-0.00-0.00i ??
 37  2 -1.456207 2.00-0.00i  0.97+0.00i -0.00+0.00i -2.00+0.00i
-0.97+0.00i  0.00+0.00i ??
 39  2 -1.241291 2.00-0.00i  0.96+0.00i  0.00+0.00i  2.00-0.00i  0.96-0.00i
-0.00-0.00i ??
 41  2 -1.240180 2.00+0.00i  0.96-0.00i -0.00-0.00i -2.00-0.00i
-0.96+0.00i  0.00-0.00i ??
 43  2 -1.239880 2.00+0.00i  0.98+0.00i  0.00+0.00i  2.00-0.00i
0.98-0.00i  0.00+0.00i ??
 45  2 -1.239851 2.00-0.00i -1.96-0.00i  0.00-0.00i  2.00-0.00i -1.96+0.00i
-0.00-0.00i ??
 47  2 -1.239461 2.00+0.00i -1.95+0.00i  0.00-0.00i -2.00-0.00i  1.95+0.00i
-0.00+0.00i ??
 49  2 -1.238950 2.00+0.00i  0.98-0.00i -0.00+0.00i -2.00-0.00i
-0.98-0.00i  0.00-0.00i ??
 51  2 -0.709844 2.00-0.00i  1.00+0.00i  0.00-0.00i  2.00-0.00i
1.00-0.00i  0.00-0.00i =G4+

Can anybody suggest why the program "irrep" did not write the parity for
some bands. Any suggestion will be appreciated.

Regards,
Bramhachari Khamari
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