[Wannier] Wannier+Shifting the dirac point of graphene

Giovanni Pizzi giovanni.pizzi at epfl.ch
Tue Jun 11 10:14:41 CEST 2013


Dear Narjes Ansari,
at a first glance your band structure seems ok to me. Did you try to compare the Wannier-interpolated band structure with the band structure calculated with your ab-initio code? Do they match?

If you are worried by the Dirac point being at a negative energy, remember that the zero of energy is set by your ab-initio code and the Fermi energy does not have to be at E=0; you have to calculate the value of the Fermi energy to know where it lies [e.g. counting the bands (for an insulator) or integrating the DOS.]

Best,
Giovanni Pizzi



On 06/11/2013 08:16 AM, Narjes Ansari wrote:
>     Dear all,
>
>
> I would like to draw the band structure for graphene. I run example 10 of
> wannier and I got graphene band structure properly. But when  I reaped
> that for  a 4-atom unit cell of the graphene Dirac point in the band
> structure of the graphene shifted to the  below the Fermi energy. Would
> some one advise me?
>
>      num_bands = 20
> num_wann  = 13
> num_iter  = 1000
>
> dis_num_iter = 1000
> dis_win_max  = 12
> dis_froz_max = 1
>
> guiding_centres = .true.
>
> mp_grid      = 1 8 8
>
> iprint       = 2
>
> num_dump_cycles = 1000
> num_print_cycles = 100
>
>
> bands_plot = true
> bands_plot_format = xmgr
>
> begin kpoint_path
> X 0.0 0.0 0.5 G 0.0 0.0 0.0
> G 0.0 0.0 0.0 Y 0.0 0.5 0.0
> Y 0.0 0.5 0.0 S 0.0 0.5 0.5
> S 0.0 0.5 0.5 X 0.0 0.0 0.5
> end kpoint_path
>
> Begin Projections
> Ang
> c=	10.0125623	,	3.909418	,	2.19878935	:pz	:z=	10.01256353	,	1.06336744	,	1.58347913	:x=0,0,1
> c=	10.0125623	,	3.198918	,	0.96816725	:pz	:z=	10.01256166	,	1.78196744	,	1.5834778	:x=0,0,1
> c=	10.0125623	,	1.777918	,	0.96816725	:pz	:z=	10.01256113	,	3.19486698	,	1.58347979	:x=0,0,1
> c=	10.0125623	,	1.067418	,	2.19878935	:pz	:z=	10.01256265	,	3.91346698	,	1.5834759	:x=0,0,1
> c=	10.01256319	,	1.4226678	,	0.35285632	:s
> c=	10.01256375	,	3.554168	,	0.3528562	:s
> c=	10.01256372	,	0.356918	,	2.19878925	:s
> c=	9.86181173	,	2.46840318	,	1.04106944	:s
> c=	10.01256112	,	3.55416698	,	1.58347889	:s
> c=	10.01256385	,	1.42266744	,	1.58347798	:s
> c=	10.01256063	,	0.356918	,	2.19878961	:s
> c=	10.01256125	,	3.55416851	,	0.35285649	:s
> c=	10.01256384	,	1.42266807	,	0.35285616	:s
> End Projections
>
> Begin Unit_Cell_Cart
> Ang
> 20.000  0.000  0.000000
>   0.000  4.263  0.000000
>   0.000  0.000  2.461244
> End Unit_Cell_Cart
>
> Begin KPoints
>    0.00000000  0.00000000  0.00000000
>    0.00000000  0.00000000  0.12500000
>    0.00000000  0.00000000  0.25000000
>    0.00000000  0.00000000  0.37500000
>    0.00000000  0.00000000  0.50000000
>    0.00000000  0.00000000  0.62500000
>    0.00000000  0.00000000  0.75000000
>    0.00000000  0.00000000  0.87500000
>    0.00000000  0.12500000  0.00000000
>    0.00000000  0.12500000  0.12500000
>    0.00000000  0.12500000  0.25000000
>    0.00000000  0.12500000  0.37500000
>    0.00000000  0.12500000  0.50000000
>    0.00000000  0.12500000  0.62500000
>    0.00000000  0.12500000  0.75000000
>    0.00000000  0.12500000  0.87500000
>    0.00000000  0.25000000  0.00000000
>    0.00000000  0.25000000  0.12500000
>    0.00000000  0.25000000  0.25000000
>    0.00000000  0.25000000  0.37500000
>    0.00000000  0.25000000  0.50000000
>    0.00000000  0.25000000  0.62500000
>    0.00000000  0.25000000  0.75000000
>    0.00000000  0.25000000  0.87500000
>    0.00000000  0.37500000  0.00000000
>    0.00000000  0.37500000  0.12500000
>    0.00000000  0.37500000  0.25000000
>    0.00000000  0.37500000  0.37500000
>    0.00000000  0.37500000  0.50000000
>    0.00000000  0.37500000  0.62500000
>    0.00000000  0.37500000  0.75000000
>    0.00000000  0.37500000  0.87500000
>    0.00000000  0.50000000  0.00000000
>    0.00000000  0.50000000  0.12500000
>    0.00000000  0.50000000  0.25000000
>    0.00000000  0.50000000  0.37500000
>    0.00000000  0.50000000  0.50000000
>    0.00000000  0.50000000  0.62500000
>    0.00000000  0.50000000  0.75000000
>    0.00000000  0.50000000  0.87500000
>    0.00000000  0.62500000  0.00000000
>    0.00000000  0.62500000  0.12500000
>    0.00000000  0.62500000  0.25000000
>    0.00000000  0.62500000  0.37500000
>    0.00000000  0.62500000  0.50000000
>    0.00000000  0.62500000  0.62500000
>    0.00000000  0.62500000  0.75000000
>    0.00000000  0.62500000  0.87500000
>    0.00000000  0.75000000  0.00000000
>    0.00000000  0.75000000  0.12500000
>    0.00000000  0.75000000  0.25000000
>    0.00000000  0.75000000  0.37500000
>    0.00000000  0.75000000  0.50000000
>    0.00000000  0.75000000  0.62500000
>    0.00000000  0.75000000  0.75000000
>    0.00000000  0.75000000  0.87500000
>    0.00000000  0.87500000  0.00000000
>    0.00000000  0.87500000  0.12500000
>    0.00000000  0.87500000  0.25000000
>    0.00000000  0.87500000  0.37500000
>    0.00000000  0.87500000  0.50000000
>    0.00000000  0.87500000  0.62500000
>    0.00000000  0.87500000  0.75000000
>    0.00000000  0.87500000  0.87500000
> End KPoints
>
> Begin Atoms_Cart
> Ang
>   C                 10.01256230    3.90941800    2.19878935
>   C                 10.01256230    3.19891800    0.96816725
>   C                 10.01256230    1.77791800    0.96816725
>   C                 10.01256230    1.06741800    2.19878935
> End Atoms_Cart
>
> Narjes Ansari
> IASBA
>
>
> _______________________________________________
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> Wannier at quantum-espresso.org
> http://www.democritos.it/mailman/listinfo/wannier


-- 
Giovanni Pizzi
Post-doctoral Research Scientist
EPFL STI IMX THEOS
MXC 340 (Bâtiment MXC)
Station 12
CH-1015 Lausanne (Switzerland)
Phone: +41 21 69 31124

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