[Wannier] bandstructure of graphene/h-BN

[徐金荣 同济大学]

Dear Wannier90's users and developers:
        Recently, I have been  fitting  the bandstructure of bilayer graphene/h-BN using vasp2wannier90 code.  The bandstructure below (figure1) is similar to DFT result's when I use fewer Kpoints (eg. KPOINTS: 5*5*1).
, 
figure 1




calculated file as below:
INCAR
step3:GW calculation
ALGO = GW0 ; LSPECTRAL = .TRUE. ; NOMEGA = 60
NBANDS=72
#LRPA = .FALSE.
LWANNIER90=.TRUE.
KPOINTS
Automatic mesh
0
G
5 5 1
POSCAR
grephene-BN 1*1*1
1.0
2.1304224933097191     -1.23           0.0
0.0                     2.46           0.0
0.0                     0.0           20.52
2 1 1
d
0.0000000000000000  -0.0000000000000000   0.5833333333333333
0.3333333333333333   0.6666666666666667   0.5833333333333333
0.0000000000000000  -0.0000000000000000   0.4166666666666667
0.6666666666666667   0.3333333333333333   0.4166666666666667
Wannier90.win
 num_wann =    12  ! set to NBANDS by VASP
 num_bands=    24
exclude_bands: 25-72


Begin Projections
#C:sp2;pz
#C:l=1,mr=1
#B:l=1,mr=1
#N:l=1,mr=1
#C:sp2;pz
#B:sp2;pz
#N:sp2;pz
C:l=1
B:l=1
N:l=1
End Projections


#dis_froz_max=9
dis_num_iter=1000


guiding_centres=true




use_bloch_phases = T


begin unit_cell_cart
     2.1304225    -1.2300000     0.0000000
     0.0000000     2.4600000     0.0000000
     0.0000000     0.0000000    20.5200000
end unit_cell_cart


begin atoms_cart
C        0.0000000     0.0000000    11.9700000
C        0.7101408     1.2300000    11.9700000
B        0.0000000     0.0000000     8.5500000
N        1.4202817     0.0000000     8.5500000
end atoms_cart


mp_grid =     5     5     1










But when I increase Kpoints to 20*20*1 in order to get high-quality results, I get wrong results (figure2) 
The calculated files are as below:
INCAR
step3:GW calculation
ALGO = GW0 ; LSPECTRAL = .TRUE. ; NOMEGA = 120
NBANDS=72
#LRPA = .FALSE.
LWANNIER90=.TRUE.
KPOINTS
Automatic mesh
0
G
20 20 1


Why the results are wrong? How should I adjust the parameters?


I look forward to receive your reply.

Thanking you and with regards.


Kinglong Xu.

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