[QE-users] Question marks (?) in band representations

박민규 minkyupark at ulsan.ac.kr
Thu Jan 21 10:09:58 CET 2021


Dear all,

I observed that question marks (?) appear in the middle of band representations (see below).
It seems similar problem occurs for the last band in some cases ( https://www.mail-archive.com/users@lists.quantum-espresso.org/msg31534.html ), but I can’t guess the reason for this case.

The material is GaAs with space group F-43m (216) and I attach scf input.
Does anyone know why they are not classified properly?

The below excerpt is on the path along Gamma to L.

 **************************************************************************

                    xk=(   0.00641,   0.00641,   0.00641  )

     double point group C_3v (3m)
     there are  6 classes and  3 irreducible representations
     the character table:

       E     -E    2C3   -2C3  3s_v  -3s_v

G_4    2.00 -2.00  1.00 -1.00  0.00  0.00
G_5    1.00 -1.00 -1.00  1.00  0.00  0.00
G_6    1.00 -1.00 -1.00  1.00  0.00  0.00

     imaginary part

       E     -E    2C3   -2C3  3s_v  -3s_v

G_4    0.00  0.00  0.00  0.00  0.00  0.00
G_5    0.00  0.00  0.00  0.00  1.00 -1.00
G_6    0.00  0.00  0.00  0.00 -1.00  1.00

     the symmetry operations in each class and the name of the first element:

     E             1

     -E           -1

     2C3           2    3

     -2C3         -2   -3

     3s_v          4    5   -6

     3s_v          6   -4   -5


     Band symmetry, C_3v (3m)   double point group:

     e(  1 -  3) =     -8.82709  eV     3   --> G_4   L_6
     e(  1 -  3) =     -8.82709  eV     3   -->   ?
     e(  4 -  4) =     -8.82688  eV     1   -->   ?
     e(  5 -  6) =     -8.39671  eV     2   --> G_4   L_6
     e(  7 -  9) =     -8.35227  eV     3   --> G_4   L_6
     e(  7 -  9) =     -8.35227  eV     3   -->   ?
     e( 10 - 10) =     -8.35203  eV     1   -->   ?
     e( 11 - 12) =     -6.25322  eV     2   --> G_4   L_6
     e( 13 - 14) =      5.88934  eV     2   --> G_4   L_6
     e( 15 - 16) =      6.17226  eV     2   --> G_4   L_6
     e( 17 - 17) =      6.22576  eV     1   -->   ?
     e( 18 - 18) =      6.22593  eV     1   -->   ?
     e( 19 - 20) =      6.33992  eV     2   --> G_4   L_6
     e( 21 - 22) =      9.71086  eV     2   --> G_4   L_6
     e( 23 - 24) =      9.90063  eV     2   --> G_4   L_6
     e( 25 - 26) =      9.90114  eV     2   --> G_5   L_4
     e( 25 - 26) =      9.90114  eV     2   --> G_6   L_5
     e( 27 - 28) =     13.62609  eV     2   --> G_4   L_6
     e( 29 - 29) =     16.14546  eV     1   -->   ?
     e( 30 - 31) =     16.14624  eV     2   --> G_4   L_6
     e( 32 - 32) =     16.14710  eV     1   -->   ?
     e( 33 - 34) =     17.64099  eV     2   --> G_4   L_6
     e( 35 - 36) =     17.67265  eV     2   --> G_4   L_6

 **************************************************************************

 **************************************************************************

                    xk=(   0.01282,   0.01282,   0.01282  )

     Band symmetry, C_3v (3m)   double point group:

     e(  1 -  1) =     -8.82718  eV     1   -->   ?
     e(  2 -  3) =     -8.82700  eV     2   --> G_4   L_6
     e(  4 -  4) =     -8.82677  eV     1   -->   ?
     e(  5 -  6) =     -8.39672  eV     2   --> G_4   L_6
     e(  7 -  7) =     -8.35236  eV     1   -->   ?
     e(  8 -  9) =     -8.35219  eV     2   --> G_4   L_6
     e( 10 - 10) =     -8.35190  eV     1   -->   ?
     e( 11 - 12) =     -6.25187  eV     2   --> G_4   L_6
     e( 13 - 14) =      5.85998  eV     2   --> G_4   L_6
     e( 15 - 16) =      6.11074  eV     2   --> G_4   L_6
     e( 17 - 17) =      6.22366  eV     1   -->   ?
     e( 18 - 18) =      6.22401  eV     1   -->   ?
     e( 19 - 20) =      6.42336  eV     2   --> G_4   L_6
     e( 21 - 22) =      9.71374  eV     2   --> G_4   L_6
     e( 23 - 24) =      9.90214  eV     2   --> G_4   L_6
     e( 25 - 26) =      9.90418  eV     2   --> G_5   L_4
     e( 25 - 26) =      9.90418  eV     2   --> G_6   L_5
     e( 27 - 28) =     13.63476  eV     2   --> G_4   L_6
     e( 29 - 29) =     16.13092  eV     1   -->   ?
     e( 30 - 31) =     16.13239  eV     2   --> G_4   L_6
     e( 32 - 32) =     16.13413  eV     1   -->   ?
     e( 33 - 34) =     17.64113  eV     2   --> G_4   L_6
     e( 35 - 36) =     17.68244  eV     2   --> G_4   L_6

 **************************************************************************

 **************************************************************************

                    xk=(   0.01923,   0.01923,   0.01923  )

     Band symmetry, C_3v (3m)   double point group:

     e(  1 -  1) =     -8.82726  eV     1   -->   ?
     e(  2 -  3) =     -8.82701  eV     2   --> G_4   L_6
     e(  4 -  4) =     -8.82664  eV     1   -->   ?
     e(  5 -  6) =     -8.39674  eV     2   --> G_4   L_6
     e(  7 -  7) =     -8.35240  eV     1   -->   ?
     e(  8 -  9) =     -8.35222  eV     2   --> G_4   L_6
     e( 10 - 10) =     -8.35171  eV     1   -->   ?
     e( 11 - 12) =     -6.24960  eV     2   --> G_4   L_6
     e( 13 - 14) =      5.80725  eV     2   --> G_4   L_6
     e( 15 - 16) =      6.06587  eV     2   --> G_4   L_6
     e( 17 - 17) =      6.22024  eV     1   -->   ?
     e( 18 - 18) =      6.22076  eV     1   -->   ?
     e( 19 - 20) =      6.50855  eV     2   --> G_4   L_6
     e( 21 - 22) =      9.71854  eV     2   --> G_4   L_6
     e( 23 - 24) =      9.90470  eV     2   --> G_4   L_6
     e( 25 - 25) =      9.90923  eV     1   -->   ?
     e( 26 - 26) =      9.90934  eV     1   -->   ?
     e( 27 - 28) =     13.64913  eV     2   --> G_4   L_6
     e( 29 - 29) =     16.10805  eV     1   -->   ?
     e( 30 - 31) =     16.11011  eV     2   --> G_4   L_6
     e( 32 - 32) =     16.11272  eV     1   -->   ?
     e( 33 - 34) =     17.63003  eV     2   --> G_4   L_6
     e( 35 - 36) =     17.70956  eV     2   --> G_4   L_6

 **************************************************************************

Best regards,
============================================
Minkyu Park
Research Institute of Basic Sciences, University of Ulsan,
93, Daehak-ro, Nam-gu, Ulsan, 44610 Republic of Korea
minkyupark at ulsan.ac.kr<mailto:minkyupark at ulsan.ac.kr>
+82-52-259-1473
============================================


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