[Pw_forum] problem of Bi2Se3 with spin orbit coupling parity analysis at TRIM points

[Andrea Dal Corso]

Quoting balabi <balabi at qq.com>:

> Dear developers,
>     previously, I send an email about symmetry analysis in calculating
> Bi2Se3 http://www.mail-archive.com/pw_forum@pwscf.org/msg31533.html
>     But I pasted the wrong input file in that email. The symmetry info in
> that post is generated for Bi2Se3 without spin orbit coupling.
>
>     Now, I calculated Bi2Se3 with spin orbit coupling. What I got is not
> right. There is no parity information labeled u and g.
>     Below is the output of bands.x for gamma point
>
> -----------------------------
> xk=(   0.00000,   0.00000,   0.00000  )
>
>      double point group C_1 (1)    
>      there are  2 classes and  1 irreducible representations
>      the character table:
>
>        E     -E   
>                   
> G_2    1.00 -1.00
>
>      the symmetry operations in each class and the name of the first
> element:
>
>      E             1
>                                                  
>                
>      -E           -1
>                                                  
>                
>
>      Band symmetry, C_1 (1)     double point group:
>
>      e(  1 -  4) =    -16.63750  eV     4   -->   4 G_2    
>        
>      e(  5 -  6) =    -16.62527  eV     2   -->   2 G_2    
>        
>      e(  7 -  8) =    -16.62265  eV     2   -->   2 G_2    
>        
>      e(  9 - 10) =    -13.66107  eV     2   -->   2 G_2      
>      
>      e( 11 - 12) =    -13.65905  eV     2   -->   2 G_2      
>      
>      e( 13 - 14) =    -13.64175  eV     2   -->   2 G_2      
>      
>      e( 15 - 16) =    -13.63940  eV     2   -->   2 G_2      
>      
>      e( 17 - 18) =    -13.63741  eV     2   -->   2 G_2      
>      
>      e( 19 - 20) =    -13.63672  eV     2   -->   2 G_2      
>      
>      e( 21 - 22) =     -6.40199  eV     2   -->   2 G_2      
>      
>      e( 23 - 24) =     -5.17683  eV     2   -->   2 G_2      
>      
>      e( 25 - 26) =     -5.15601  eV     2   -->   2 G_2      
>      
>      e( 27 - 28) =     -1.79777  eV     2   -->   2 G_2      
>      
>      e( 29 - 30) =     -1.02045  eV     2   -->   2 G_2      
>      
>      e( 31 - 32) =      5.18513  eV     2   -->   2 G_2      
>      
>      e( 33 - 34) =      5.40747  eV     2   -->   2 G_2      
>      
>      e( 35 - 36) =      6.03590  eV     2   -->   2 G_2      
>      
>      e( 37 - 38) =      6.14972  eV     2   -->   2 G_2      
>      
>      e( 39 - 40) =      6.19631  eV     2   -->   2 G_2      
>      
>      e( 41 - 42) =      6.51310  eV     2   -->   2 G_2      
>      
>      e( 43 - 44) =      6.80580  eV     2   -->   2 G_2      
>      
>      e( 45 - 46) =      7.20470  eV     2   -->   2 G_2      
>      
>      e( 47 - 48) =      7.50637  eV     2   -->   2 G_2      
>      
>      e( 49 - 50) =      8.05825  eV     2   -->   2 G_2      
>      
>      e( 51 - 52) =      9.13333  eV     2   -->   2 G_2      
>      
>      e( 53 - 54) =      9.27043  eV     2   -->   2 G_2      
>      
>      e( 55 - 56) =      9.86223  eV     2   -->   2 G_2      
>      
>      e( 57 - 58) =     11.09081  eV     2   -->   2 G_2      
>      
>      e( 59 - 60) =     11.46791  eV     2   -->   2 G_2      
>      
>      e( 61 - 62) =     13.77176  eV     2   -->   2 G_2      
>      
>      e( 63 - 64) =     14.35855  eV     2   -->   2 G_2    
>
> ----------------------
>
> Is this right? There are no u and g like Bi2Se3 without SOC. How can I tell
> the parity? And the symmetry seems too simple.
>
> ----------------------
>
> below is my Bi2Se3 with SOC bands.in
>
> &CONTROL
> prefix='Bi2Se3_SOC',
> calculation='bands',
> restart_mode='from_scratch',
> wf_collect=.true.,
> verbosity='high',
> outdir='./quantum_espresso/qe_tmpdir',
> pseudo_dir='./quantum_espresso/pseudo',
> /
> &SYSTEM
> ibrav = -5,celldm(1) =18.5969068371645,celldm(4)=0.9115970970052608,nat =
> 5,ntyp = 3,
> ecutwfc = 40,ecutrho = 500,
> noncolin=.true.,lspinorb=.true.,starting_magnetization=0.,
> nbnd=64,
> nosym=.true.,


nosym=.TRUE. means that no symmetry is used.

HTH,

Andrea


> /
> &ELECTRONS
> conv_thr = 1.0d-10,  !default 1d-6
> diago_full_acc=.true.,!increase empty bands accuracy
> /
> ATOMIC_SPECIES
> Bi 208.98040  Bi.rel-pbe-dn-kjpaw_psl.0.2.2.UPF
> Se178.971Se.rel-pbe-n-kjpaw_psl.0.2.UPF
> Se278.971Se.rel-pbe-n-kjpaw_psl.0.2.UPF
> ATOMIC_POSITIONS crystal
> Bi0.39900.39900.3990
> Bi0.60100.60100.6010
> Se11.00001.00001.0000
> Se20.20600.20600.2060
> Se20.79400.79400.7940
> K_POINTS crystal_b
> 5
> 0.00000      0.00000      0.00000     1 !gG
> 0.50000      0.50000      0.50000     1 !Z
> 0.50000      0.50000     -0.00000     1 !F
> 0.00000      0.00000      0.00000     1 !gG
> 0.00000      0.00000     -0.50000     1  !L1