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hi ,every here ?
i am now calculating graphene ,a two demension semi-metal ,zero gap.so i tried sigma=0 and sigma=1 to calulated dos respectively.
and i found when i use THE PARAMETE
ENCUT=500
PREC=A
EDIFF=1E-6
ISMEAR=1
SIGMA=0.0NEDOS=1001
NBANDS=8
LOPTICS=.T.
NPAR=1
LWAVE=.F.
the doscar list all the occupation is zero at all the energies.
but i lookde at the occupation in the outcar ,not that case , k-point 643 : 0.2000 0.1000 0.0000
band No. band energies occupation
1 -19.2115 2.00000
2 -8.7852 2.00000
3 -7.2001 2.00000
4 -7.1174 2.00000
5 4.1158 0.00000
6 5.5931 0.00000
7 5.8635 0.00000
8 6.9209 0.00000

k-point 644 : 0.2083 0.1000 0.0000
band No. band energies occupation
1 -19.1126 2.00000
2 -8.9891 2.00000
3 -7.2098 2.00000
4 -7.0843 2.00000
5 4.2528 0.00000
6 5.4344 0.00000
7 5.9394 0.00000
8 7.0530 0.00000

k-point 645 : 0.2167 0.1000 0.0000
band No. band energies occupation
1 -19.0106 2.00000
2 -9.1952 2.00000
3 -7.2996 2.00000
4 -6.9652 2.00000
5 4.3942 0.00000
6 5.2302 0.00000
7 6.0629 0.00000

many kpoints have the same occupation like above .
so there is a inconsistency ? i am woudering ,does the sigma=0 cause ? in my idea, the sigma is uesd to accelerate
convergence ,and here ,i use 0 also can convergence .


and a anther question maybe more fundamental how to choose the ismearing and sigma as to the zero-gap semi-metal ,like one-layer graphene?


i will appreciate if anyone would give me som hints


best regard
xu

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