Re: [Wien] Graphene bandstructure

2015-12-23 Thread Islam, Md F
Hi Xavier,

Thanks for attaching the cif file. You are right that I didn't consider any 
particular
symmetry. I just built the structure with the known lattice parameters from the 
literature.
I thought if I have correct structure I would get correct SCF result even if I 
don't take 
advantage of all available symmetry, even though it takes more time. Anyway, I 
will
try with this structure now.


Best regards,
Fhokrul  



From: wien-boun...@zeus.theochem.tuwien.ac.at 
[wien-boun...@zeus.theochem.tuwien.ac.at] On Behalf Of Xavier Rocquefelte 
[xavier.rocquefe...@univ-rennes1.fr]
Sent: Wednesday, December 23, 2015 6:54 AM
To: A Mailing list for WIEN2k users
Subject: Re: [Wien] Graphene bandstructure

Dear Fhokrul
Your structure looks strange to me. The angle is 60° and not 120° and it seems 
that you do not take benefit of the symetry.
Here is a cif file of graphene based on the graphite structure in which I have 
simply increase the c parameter.
The structure you are using may explain why you still have a gap (symetry 
problem).
Best Regards
Xavier


#==

# CRYSTAL DATA

#--

data_VESTA_phase_1


_pd_phase_name 'C'
_cell_length_a 2.45600
_cell_length_b 2.45600
_cell_length_c 15.0
_cell_angle_alpha  90
_cell_angle_beta   90
_cell_angle_gamma  120
_symmetry_space_group_name_H-M 'P 63 m c'
_symmetry_Int_Tables_number186

loop_
_symmetry_equiv_pos_as_xyz
'x, y, z'
'-y, x-y, z'
'-x+y, -x, z'
'-x, -y, z+1/2'
'y, -x+y, z+1/2'
'x-y, x, z+1/2'
'-y, -x, z'
'-x+y, y, z'
'x, x-y, z'
'y, x, z+1/2'
'x-y, -y, z+1/2'
'-x, -x+y, z+1/2'

loop_
_atom_site_label
_atom_site_occupancy
_atom_site_fract_x
_atom_site_fract_y
_atom_site_fract_z
_atom_site_adp_type
_atom_site_B_iso_or_equiv
_atom_site_type_symbol
C1 1.0 0.00  0.00  0.00 Biso  1.00 C
C2 1.0 0.33  0.67  0.00 Biso  1.00 C



"Islam, Md F" <isl...@uta.edu> a écrit :

> Sorry, in my earlier email, I meant to say with 30 x 30 x 1 mesh, gap
> is smaller but
> it doesn't close completely.
>
> Thanks,
> Fhokrul
>
>
> 
> From: wien-boun...@zeus.theochem.tuwien.ac.at
> [wien-boun...@zeus.theochem.tuwien.ac.at] On Behalf Of Islam, Md F
> [isl...@uta.edu]
> Sent: Wednesday, December 23, 2015 6:22 AM
> To: A Mailing list for WIEN2k users
> Subject: Re: [Wien] Graphene bandstructure
>
> Hi Prof Blaha,
>
> Here is the structure I am using. I tried to be as precise as
> possible with position coordinates.
> I think size of the vacuum is sufficiently large so that
> supercell-supercell interaction is negligible.
> So far what I have got is that with LDA xc if I use 25 x 25 x 1
> k-mesh there is a gap at the Fermi
> level (which passes through K point) but if I use 30 x 30 x 1 k-mesh,
> gap closes but DOS is not
> zero at the Fermi level (about 0.001/eV). Please let me know if I am
> doing anything wrong with
> this calculation.
>
>
> Thanks,
> Fhokrul
>
>
> Graphene
> P LATTICE,NONEQUIV.ATOMS: 2
> MODE OF CALC=RELA unit=bohr
> 4.647800 4.647800 30.00 90.00 90.00 60.00
> ATOM -1: X=0. Y=0. Z=0.5000
>  MULT= 1 ISPLIT= 8
> C NPT= 781 R0=0.0001 RMT= 1.3200 Z: 6.0
> LOCAL ROT MATRIX:1.000 0.000 0.000
>0.000 1.000 0.000
>0.000 0.000 1.000
> ATOM -2: X=0.6667 Y=0.6667 Z=0.5000
>  MULT= 1 ISPLIT= 8
> C NPT= 781 R0=0.0001 RMT= 1.3200 Z: 6.0
> LOCAL ROT MATRIX: 1.000 0.000 0.000
> 0.000 1.000 0.000
> 0.000 0.000 1.000
> 12 NUMBER OF SYMMETRY OPERATIONS
> -1-1 0 0.
> 0 1 0 0.
> 0 0-1 0.
> 1
> -1-1 0 0.
> 0 1 0 0.
> 0 0 1 0.
> 2
> -1-1 0 0.
> 1 0 0 0.
> 0 0-1 0.
> 3
> -1-1 0 0.
> 1 0 0 0.
> 0 0 1 0.
> 4
> 0 1 0 0.
> -1-1 0 0.
> 0 0-1 0.
> 5
> 0 1 0 0.
> -1-1 0 0.
> 0 0 1 0.
> 6
> 0 1 0 0.
> 1 0 0 0.
> 0 0-1 0.
> 7
> 0 1 0 0.
> 1 0 0 0.
> 0 0 1 0.
> 8
> 1 0 0 0.
> -1-1 0 0.
> 0 0-1 0.
> 9
> 1 0 0 0.0

Re: [Wien] Graphene bandstructure

2015-12-23 Thread Islam, Md F
Thank you very much for your suggestions/comments. 

a) I will create a new structure with H symmetry.

b) I actually answered in one of my previous emails that I have calculated 
the gap from bandstructure. Using xmgrace I zoomed in on K point
and found that there is a gap. I tried to use :GAP as you mentioned
before but mesh size was probably not compatible with the pattern you
mentioned, so I didn't get anything.

Thanks again,
Fhokrul





From: wien-boun...@zeus.theochem.tuwien.ac.at 
[wien-boun...@zeus.theochem.tuwien.ac.at] On Behalf Of Peter Blaha 
[pbl...@theochem.tuwien.ac.at]
Sent: Wednesday, December 23, 2015 6:57 AM
To: A Mailing list for WIEN2k users
Subject: Re: [Wien] Graphene bandstructure

a) As expected, something is wrong with your structure.

It should be a hexagonal lattice   (H  and not P) and the angle gamma
should be 120 and not 60, and also the positions need to be changed then.

With an "H" lattice, wien2k keeps the symmetry properly and is less
affected by rounding errors.

b) And secondly, you did not answer, how you got the "gap" (from
scf-file, output1 or bandstructure or DOS ???)

Forget DOS (there is a smearing parameter set by default !)

when you use a H lattice and meshes which can be divided by 3 (because K
has 1/3,1/3,0 coordinates and only with  a mesh like 3 3 1, 6 6 1, 9 9
1, ...   the "K"-point is in the mesh), you can use :GAP from scf,
otherwise NOT.  (best is to use a mesh conpatible with 2 and 3, so 6,6,1
or 12,12,1 ..., because this includes also the M point.



On 12/23/2015 01:22 PM, Islam, Md F wrote:
> Hi Prof Blaha,
>
>  Here is the structure I am using. I tried to be as precise as possible 
> with position coordinates.
> I think size of the vacuum is sufficiently large so that supercell-supercell 
> interaction is negligible.
> So far what I have got is that with LDA xc if I use 25 x 25 x 1 k-mesh there 
> is a gap at the Fermi
> level (which passes through K point) but if I use 30 x 30 x 1 k-mesh, gap 
> closes but DOS is not
> zero at the Fermi level (about 0.001/eV). Please let me know if I am doing 
> anything wrong with
> this calculation.
>
>
> Thanks,
> Fhokrul
>
>
> Graphene
> P LATTICE,NONEQUIV.ATOMS: 2
> MODE OF CALC=RELA unit=bohr
> 4.647800 4.647800 30.00 90.00 90.00 60.00
> ATOM -1: X=0. Y=0. Z=0.5000
>   MULT= 1 ISPLIT= 8
> C NPT= 781 R0=0.0001 RMT= 1.3200 Z: 6.0
> LOCAL ROT MATRIX:1.000 0.000 0.000
> 0.000 1.000 0.000
> 0.000 0.000 1.000
> ATOM -2: X=0.6667 Y=0.6667 Z=0.5000
>   MULT= 1 ISPLIT= 8
> C NPT= 781 R0=0.0001 RMT= 1.3200 Z: 6.0
> LOCAL ROT MATRIX: 1.000 0.000 0.000
>  0.000 1.000 0.000
>  0.000 0.000 1.000
> 12 NUMBER OF SYMMETRY OPERATIONS
> -1-1 0 0.
> 0 1 0 0.
> 0 0-1 0.
> 1
> -1-1 0 0.
> 0 1 0 0.
> 0 0 1 0.
> 2
> -1-1 0 0.
> 1 0 0 0.
> 0 0-1 0.
> 3
> -1-1 0 0.
> 1 0 0 0.
> 0 0 1 0.
> 4
> 0 1 0 0.
> -1-1 0 0.
> 0 0-1 0.
> 5
> 0 1 0 0.
> -1-1 0 0.
> 0 0 1 0.
> 6
> 0 1 0 0.
> 1 0 0 0.
> 0 0-1 0.
> 7
> 0 1 0 0.
> 1 0 0 0.
> 0 0 1 0.
> 8
> 1 0 0 0.
> -1-1 0 0.
> 0 0-1 0.
> 9
> 1 0 0 0.
> -1-1 0 0.
> 0 0 1 0.
> 10
> 1 0 0 0.
> 0 1 0 0.
> 0 0-1 0.
> 11
> 1 0 0 0.
> 0 1 0 0.
> 0 0 1 0.
> 12
>
>
>
>
> ________
> From: wien-boun...@zeus.theochem.tuwien.ac.at 
> [wien-boun...@zeus.theochem.tuwien.ac.at] On Behalf Of Peter Blaha 
> [pbl...@theochem.tuwien.ac.at]
> Sent: Tuesday, December 22, 2015 3:29 PM
> To: A Mailing list for WIEN2k users
> Subject: Re: [Wien] Graphene bandstructure
>
> The two eigenvalues at K must be identical by symmetry.
>
> If you have a splitting of some meV it means that your structure is
> slightly wrong.
>
> Typical errors: positions of 1/3 and 2/3 must be given in full precision.
>0.   is NOT 1/3
>
> Am 22.12.2015 um 20:31 schrieb Islam, Md F:
>> Hi Prof Blaha,
>>
>>   I have got the gap from plotting bandstructure as well as DOS 
>> calculations.
>> I can see the linear dispersion at the K point just like the way it is 
>> suppos

Re: [Wien] Graphene bandstructure

2015-12-23 Thread Laurence Marks
As a small addendum, you may also need to ensure that the fft size in lapw0
(via case.in0) is a multiple of 6 along a & b to preserve equivalence of
atoms.

---
Professor Laurence Marks
Department of Materials Science and Engineering
Northwestern University
http://www.numis.northwestern.edu
Corrosion in 4D http://MURI4D.numis.northwestern.edu
Co-Editor, Acta Cryst A
"Research is to see what everybody else has seen, and to think what nobody
else has thought"
Albert Szent-Gyorgi
On Dec 23, 2015 06:57, "Peter Blaha" <pbl...@theochem.tuwien.ac.at> wrote:

> a) As expected, something is wrong with your structure.
>
> It should be a hexagonal lattice   (H  and not P) and the angle gamma
> should be 120 and not 60, and also the positions need to be changed then.
>
> With an "H" lattice, wien2k keeps the symmetry properly and is less
> affected by rounding errors.
>
> b) And secondly, you did not answer, how you got the "gap" (from
> scf-file, output1 or bandstructure or DOS ???)
>
> Forget DOS (there is a smearing parameter set by default !)
>
> when you use a H lattice and meshes which can be divided by 3 (because K
> has 1/3,1/3,0 coordinates and only with  a mesh like 3 3 1, 6 6 1, 9 9
> 1, ...   the "K"-point is in the mesh), you can use :GAP from scf,
> otherwise NOT.  (best is to use a mesh conpatible with 2 and 3, so 6,6,1
> or 12,12,1 ..., because this includes also the M point.
>
>
>
> On 12/23/2015 01:22 PM, Islam, Md F wrote:
> > Hi Prof Blaha,
> >
> >  Here is the structure I am using. I tried to be as precise as
> possible with position coordinates.
> > I think size of the vacuum is sufficiently large so that
> supercell-supercell interaction is negligible.
> > So far what I have got is that with LDA xc if I use 25 x 25 x 1 k-mesh
> there is a gap at the Fermi
> > level (which passes through K point) but if I use 30 x 30 x 1 k-mesh,
> gap closes but DOS is not
> > zero at the Fermi level (about 0.001/eV). Please let me know if I am
> doing anything wrong with
> > this calculation.
> >
> >
> > Thanks,
> > Fhokrul
> >
> >
> > Graphene
> > P LATTICE,NONEQUIV.ATOMS: 2
> > MODE OF CALC=RELA unit=bohr
> > 4.647800 4.647800 30.00 90.00 90.00 60.00
> > ATOM -1: X=0. Y=0. Z=0.5000
> >   MULT= 1 ISPLIT= 8
> > C NPT= 781 R0=0.0001 RMT= 1.3200 Z: 6.0
> > LOCAL ROT MATRIX:1.000 0.000 0.000
> > 0.000 1.000 0.000
> > 0.000 0.000 1.000
> > ATOM -2: X=0.6667 Y=0.6667 Z=0.5000
> >   MULT= 1 ISPLIT= 8
> > C NPT= 781 R0=0.0001 RMT= 1.3200 Z: 6.0
> > LOCAL ROT MATRIX: 1.000 0.000 0.000
> >  0.000 1.000 0.000
> >  0.000 0.000 1.000
> > 12 NUMBER OF SYMMETRY OPERATIONS
> > -1-1 0 0.
> > 0 1 0 0.
> > 0 0-1 0.
> > 1
> > -1-1 0 0.
> > 0 1 0 0.
> > 0 0 1 0.
> > 2
> > -1-1 0 0.
> > 1 0 0 0.
> > 0 0-1 0.
> > 3
> > -1-1 0 0.
> > 1 0 0 0.
> > 0 0 1 0.
> > 4
> > 0 1 0 0.
> > -1-1 0 0.
> > 0 0-1 0.
> > 5
> > 0 1 0 0.
> > -1-1 0 0.
> > 0 0 1 0.
> > 6
> > 0 1 0 0.
> > 1 0 0 0.
> > 0 0-1 0.
> > 7
> > 0 1 0 0.
> > 1 0 0 0.
> > 0 0 1 0.
> > 8
> > 1 0 0 0.
> > -1-1 0 0.
> > 0 0-1 0.00000000
> > 9
> > 1 0 0 0.
> > -1-1 0 0.
> > 0 0 1 0.
> > 10
> > 1 0 0 0.
> > 0 1 0 0.
> > 0 0-1 0.
> > 11
> > 1 0 0 0.
> > 0 1 0 0.
> > 0 0 1 0.
> > 12
> >
> >
> >
> >
> > 
> > From: wien-boun...@zeus.theochem.tuwien.ac.at [
> wien-boun...@zeus.theochem.tuwien.ac.at] On Behalf Of Peter Blaha [
> pbl...@theochem.tuwien.ac.at]
> > Sent: Tuesday, December 22, 2015 3:29 PM
> > To: A Mailing list for WIEN2k users
> > Subject: Re: [Wien] Graphene bandstructure
> >
> > The two eigenvalues at K must be identical by symmetry.
> >
> > If you have a splitting of some meV it means that your structure is
> > slightly wrong.
> >
> > Typical e

Re: [Wien] Graphene bandstructure

2015-12-23 Thread Islam, Md F
It is multiple of 6  along a & b in case.in0 file.

Thanks,
Fhokrul



From: wien-boun...@zeus.theochem.tuwien.ac.at 
[wien-boun...@zeus.theochem.tuwien.ac.at] On Behalf Of Laurence Marks 
[laurence.ma...@gmail.com]
Sent: Wednesday, December 23, 2015 7:04 AM
To: A Mailing list for WIEN2k users
Subject: Re: [Wien] Graphene bandstructure

As a small addendum, you may also need to ensure that the fft size in lapw0 
(via case.in0) is a multiple of 6 along a & b to preserve equivalence of atoms.

---
Professor Laurence Marks
Department of Materials Science and Engineering
Northwestern University
http://www.numis.northwestern.edu
Corrosion in 4D http://MURI4D.numis.northwestern.edu
Co-Editor, Acta Cryst A
"Research is to see what everybody else has seen, and to think what nobody else 
has thought"
Albert Szent-Gyorgi

On Dec 23, 2015 06:57, "Peter Blaha" 
<pbl...@theochem.tuwien.ac.at<mailto:pbl...@theochem.tuwien.ac.at>> wrote:
a) As expected, something is wrong with your structure.

It should be a hexagonal lattice   (H  and not P) and the angle gamma
should be 120 and not 60, and also the positions need to be changed then.

With an "H" lattice, wien2k keeps the symmetry properly and is less
affected by rounding errors.

b) And secondly, you did not answer, how you got the "gap" (from
scf-file, output1 or bandstructure or DOS ???)

Forget DOS (there is a smearing parameter set by default !)

when you use a H lattice and meshes which can be divided by 3 (because K
has 1/3,1/3,0 coordinates and only with  a mesh like 3 3 1, 6 6 1, 9 9
1, ...   the "K"-point is in the mesh), you can use :GAP from scf,
otherwise NOT.  (best is to use a mesh conpatible with 2 and 3, so 6,6,1
or 12,12,1 ..., because this includes also the M point.



On 12/23/2015 01:22 PM, Islam, Md F wrote:
> Hi Prof Blaha,
>
>  Here is the structure I am using. I tried to be as precise as possible 
> with position coordinates.
> I think size of the vacuum is sufficiently large so that supercell-supercell 
> interaction is negligible.
> So far what I have got is that with LDA xc if I use 25 x 25 x 1 k-mesh there 
> is a gap at the Fermi
> level (which passes through K point) but if I use 30 x 30 x 1 k-mesh, gap 
> closes but DOS is not
> zero at the Fermi level (about 0.001/eV). Please let me know if I am doing 
> anything wrong with
> this calculation.
>
>
> Thanks,
> Fhokrul
>
>
> Graphene
> P LATTICE,NONEQUIV.ATOMS: 2
> MODE OF CALC=RELA unit=bohr
> 4.647800 4.647800 30.00 90.00 90.00 60.00
> ATOM -1: X=0. Y=0. Z=0.5000
>   MULT= 1 ISPLIT= 8
> C NPT= 781 R0=0.0001 RMT= 1.3200 Z: 6.0
> LOCAL ROT MATRIX:1.000 0.000 0.000
> 0.000 1.000 0.000
> 0.000 0.000 1.000
> ATOM -2: X=0.6667 Y=0.6667 Z=0.5000
>   MULT= 1 ISPLIT= 8
> C NPT= 781 R0=0.0001 RMT= 1.3200 Z: 6.0
> LOCAL ROT MATRIX: 1.000 0.000 0.000
>  0.000 1.000 0.000
>  0.000 0.000 1.000
> 12 NUMBER OF SYMMETRY OPERATIONS
> -1-1 0 0.
> 0 1 0 0.
> 0 0-1 0.
> 1
> -1-1 0 0.
> 0 1 0 0.
> 0 0 1 0.
> 2
> -1-1 0 0.
> 1 0 0 0.
> 0 0-1 0.
> 3
> -1-1 0 0.
> 1 0 0 0.
> 0 0 1 0.
> 4
> 0 1 0 0.
> -1-1 0 0.
> 0 0-1 0.
> 5
> 0 1 0 0.
> -1-1 0 0.
> 0 0 1 0.
> 6
> 0 1 0 0.
> 1 0 0 0.
> 0 0-1 0.
> 7
> 0 1 0 0.
> 1 0 0 0.
> 0 0 1 0.
> 8
> 1 0 0 0.
> -1-1 0 0.
> 0 0-1 0.
> 9
> 1 0 0 0.
> -1-1 0 0.
> 0 0 1 0.
> 10
> 1 0 0 0.
> 0 1 0 0.
> 0 0-1 0.
> 11
> 1 0 0 0.
> 0 1 0 0.
> 0 0 1 0.
> 12
>
>
>
>
> 
> From: 
> wien-boun...@zeus.theochem.tuwien.ac.at<mailto:wien-boun...@zeus.theochem.tuwien.ac.at>
>  
> [wien-boun...@zeus.theochem.tuwien.ac.at<mailto:wien-boun...@zeus.theochem.tuwien.ac.at>]
>  On Behalf Of Peter Blaha 
> [pbl...@theochem.tuwien.ac.at<mailto:pbl...@theochem.tuwien.ac.at>]
> Sent: Tuesday, December 22, 2015 3:29 PM
> To: A Mailing list for WIEN2k users
> Subject: Re: [Wien] Graphene bandstructure
>
> The two eigenvalues at K must be identical by symmetry.
>
> If you have a splitting of some meV it means that your structure is
> slightly wro

Re: [Wien] Graphene bandstructure

2015-12-23 Thread Islam, Md F
Hi Prof Blaha,

Here is the structure I am using. I tried to be as precise as possible with 
position coordinates. 
I think size of the vacuum is sufficiently large so that supercell-supercell 
interaction is negligible.
So far what I have got is that with LDA xc if I use 25 x 25 x 1 k-mesh there is 
a gap at the Fermi 
level (which passes through K point) but if I use 30 x 30 x 1 k-mesh, gap 
closes but DOS is not 
zero at the Fermi level (about 0.001/eV). Please let me know if I am doing 
anything wrong with
this calculation.


Thanks,
Fhokrul


Graphene 
P LATTICE,NONEQUIV.ATOMS: 2 
MODE OF CALC=RELA unit=bohr 
4.647800 4.647800 30.00 90.00 90.00 60.00 
ATOM -1: X=0. Y=0. Z=0.5000
 MULT= 1 ISPLIT= 8
C NPT= 781 R0=0.0001 RMT= 1.3200 Z: 6.0 
LOCAL ROT MATRIX:1.000 0.000 0.000
   0.000 1.000 0.000
   0.000 0.000 1.000
ATOM -2: X=0.6667 Y=0.6667 Z=0.5000
 MULT= 1 ISPLIT= 8
C NPT= 781 R0=0.0001 RMT= 1.3200 Z: 6.0 
LOCAL ROT MATRIX: 1.000 0.000 0.000
0.000 1.000 0.000
0.000 0.000 1.000
12 NUMBER OF SYMMETRY OPERATIONS
-1-1 0 0.
0 1 0 0.
0 0-1 0.
1
-1-1 0 0.
0 1 0 0.
0 0 1 0.
2
-1-1 0 0.
1 0 0 0.
0 0-1 0.
3
-1-1 0 0.
1 0 0 0.
0 0 1 0.
4
0 1 0 0.
-1-1 0 0.
0 0-1 0.
5
0 1 0 0.
-1-1 0 0.
0 0 1 0.
6
0 1 0 0.
1 0 0 0.
0 0-1 0.
7
0 1 0 0.
1 0 0 0.
0 0 1 0.
8
1 0 0 0.
-1-1 0 0.
0 0-1 0.
9
1 0 0 0.
-1-1 0 0.
0 0 1 0.
10
1 0 0 0.
0 1 0 0.
0 0-1 0.
11
1 0 0 0.
0 1 0 0.
0 0 1 0.
12





From: wien-boun...@zeus.theochem.tuwien.ac.at 
[wien-boun...@zeus.theochem.tuwien.ac.at] On Behalf Of Peter Blaha 
[pbl...@theochem.tuwien.ac.at]
Sent: Tuesday, December 22, 2015 3:29 PM
To: A Mailing list for WIEN2k users
Subject: Re: [Wien] Graphene bandstructure

The two eigenvalues at K must be identical by symmetry.

If you have a splitting of some meV it means that your structure is
slightly wrong.

Typical errors: positions of 1/3 and 2/3 must be given in full precision.
  0.   is NOT 1/3

Am 22.12.2015 um 20:31 schrieb Islam, Md F:
> Hi Prof Blaha,
>
>  I have got the gap from plotting bandstructure as well as DOS 
> calculations.
> I can see the linear dispersion at the K point just like the way it is 
> suppose to be
> when I plot all the bands in eV range. But if I zoom in at the K point in meV 
> range,
> I can see the gap.
>
> I don't think there is anything wrong with the structure. I did check all 
> bond lengths,
> angles before I ran the calculations and they are correct. I suspect I may 
> have to adjust
> parameters. I started to see some difference with LDA xc functional with 
> larger k mesh.
>
>
> Thanks,
> Fhokrul
>
>
>
>
> 
> From: wien-boun...@zeus.theochem.tuwien.ac.at 
> [wien-boun...@zeus.theochem.tuwien.ac.at] On Behalf Of Peter Blaha 
> [pbl...@theochem.tuwien.ac.at]
> Sent: Tuesday, December 22, 2015 11:35 AM
> To: A Mailing list for WIEN2k users
> Subject: Re: [Wien] Graphene bandstructure
>
> Graphene is metallic by "symmetry", i.e. EF is at a 2-fold eigenvalue at
> the K-point and bands cross with a linear dispersion.
>
>   From where do you know that graphene has a gap in your calculations ??
>
>   From :gap in the scf file or from plotting the bandstructure or ...
>
> It the state at K is not degenerate, you have the wrong symmetry and are
> not doing graphene.
>
> Am 22.12.2015 um 16:51 schrieb Islam, Md F:
>> Hi,
>>
>>I am trying to do a bandstructure calculation of graphene to check if 
>> I can
>> reproduce results discussed in literature (I am using a unit cell of 2 
>> atoms).
>> With spin-orbit coupling, there should be a gap of the order of few micro-eV
>> and without spin-orbit, there should not be any gap at Dirac point. But I am
>> getting a gap of meV even without spin-orbit. I tried both GGA and LDA with
>> very dense mesh but the gap does not close. So I am wondering if anyone
>> have any suggestion about how to do it in Wien2k.
>>
>>
>> Thanks,
>> Fhokrul
>> ___
>> Wien mailing list
>> Wien@zeus.theochem.tuwien.ac.at
>> http://zeus.theochem.tuwien.ac.at/mailman/listinfo/wien
>> SEARCH the MAILING-LIST at: 

Re: [Wien] Graphene bandstructure

2015-12-23 Thread Islam, Md F
Sorry, in my earlier email, I meant to say with 30 x 30 x 1 mesh, gap is 
smaller but
it doesn't close completely.

Thanks,
Fhokrul



From: wien-boun...@zeus.theochem.tuwien.ac.at 
[wien-boun...@zeus.theochem.tuwien.ac.at] On Behalf Of Islam, Md F 
[isl...@uta.edu]
Sent: Wednesday, December 23, 2015 6:22 AM
To: A Mailing list for WIEN2k users
Subject: Re: [Wien] Graphene bandstructure

Hi Prof Blaha,

Here is the structure I am using. I tried to be as precise as possible with 
position coordinates.
I think size of the vacuum is sufficiently large so that supercell-supercell 
interaction is negligible.
So far what I have got is that with LDA xc if I use 25 x 25 x 1 k-mesh there is 
a gap at the Fermi
level (which passes through K point) but if I use 30 x 30 x 1 k-mesh, gap 
closes but DOS is not
zero at the Fermi level (about 0.001/eV). Please let me know if I am doing 
anything wrong with
this calculation.


Thanks,
Fhokrul


Graphene
P LATTICE,NONEQUIV.ATOMS: 2
MODE OF CALC=RELA unit=bohr
4.647800 4.647800 30.00 90.00 90.00 60.00
ATOM -1: X=0. Y=0. Z=0.5000
 MULT= 1 ISPLIT= 8
C NPT= 781 R0=0.0001 RMT= 1.3200 Z: 6.0
LOCAL ROT MATRIX:1.000 0.000 0.000
   0.000 1.000 0.000
   0.000 0.000 1.000
ATOM -2: X=0.6667 Y=0.6667 Z=0.5000
 MULT= 1 ISPLIT= 8
C NPT= 781 R0=0.0001 RMT= 1.3200 Z: 6.0
LOCAL ROT MATRIX: 1.000 0.000 0.000
0.000 1.000 0.000
0.000 0.000 1.000
12 NUMBER OF SYMMETRY OPERATIONS
-1-1 0 0.
0 1 0 0.
0 0-1 0.
1
-1-1 0 0.
0 1 0 0.
0 0 1 0.
2
-1-1 0 0.
1 0 0 0.
0 0-1 0.
3
-1-1 0 0.
1 0 0 0.
0 0 1 0.
4
0 1 0 0.
-1-1 0 0.
0 0-1 0.
5
0 1 0 0.
-1-1 0 0.
0 0 1 0.
6
0 1 0 0.
1 0 0 0.
0 0-1 0.
7
0 1 0 0.
1 0 0 0.
0 0 1 0.
8
1 0 0 0.
-1-1 0 0.
0 0-1 0.
9
1 0 0 0.
-1-1 0 0.
0 0 1 0.
10
1 0 0 0.
0 1 0 0.
0 0-1 0.
11
1 0 0 0.
0 1 0 0.
0 0 1 0.
12





From: wien-boun...@zeus.theochem.tuwien.ac.at 
[wien-boun...@zeus.theochem.tuwien.ac.at] On Behalf Of Peter Blaha 
[pbl...@theochem.tuwien.ac.at]
Sent: Tuesday, December 22, 2015 3:29 PM
To: A Mailing list for WIEN2k users
Subject: Re: [Wien] Graphene bandstructure

The two eigenvalues at K must be identical by symmetry.

If you have a splitting of some meV it means that your structure is
slightly wrong.

Typical errors: positions of 1/3 and 2/3 must be given in full precision.
  0.   is NOT 1/3

Am 22.12.2015 um 20:31 schrieb Islam, Md F:
> Hi Prof Blaha,
>
>  I have got the gap from plotting bandstructure as well as DOS 
> calculations.
> I can see the linear dispersion at the K point just like the way it is 
> suppose to be
> when I plot all the bands in eV range. But if I zoom in at the K point in meV 
> range,
> I can see the gap.
>
> I don't think there is anything wrong with the structure. I did check all 
> bond lengths,
> angles before I ran the calculations and they are correct. I suspect I may 
> have to adjust
> parameters. I started to see some difference with LDA xc functional with 
> larger k mesh.
>
>
> Thanks,
> Fhokrul
>
>
>
>
> 
> From: wien-boun...@zeus.theochem.tuwien.ac.at 
> [wien-boun...@zeus.theochem.tuwien.ac.at] On Behalf Of Peter Blaha 
> [pbl...@theochem.tuwien.ac.at]
> Sent: Tuesday, December 22, 2015 11:35 AM
> To: A Mailing list for WIEN2k users
> Subject: Re: [Wien] Graphene bandstructure
>
> Graphene is metallic by "symmetry", i.e. EF is at a 2-fold eigenvalue at
> the K-point and bands cross with a linear dispersion.
>
>   From where do you know that graphene has a gap in your calculations ??
>
>   From :gap in the scf file or from plotting the bandstructure or ...
>
> It the state at K is not degenerate, you have the wrong symmetry and are
> not doing graphene.
>
> Am 22.12.2015 um 16:51 schrieb Islam, Md F:
>> Hi,
>>
>>I am trying to do a bandstructure calculation of graphene to check if 
>> I can
>> reproduce results discussed in literature (I am using a unit cell of 2 
>> atoms).
>> With spin-orbit coupling, there should be a gap of the order of few micro-eV
>> and without spin-orbit, there should not be any gap at Dirac point. But I am
>> getting a gap of meV even without spin

Re: [Wien] Graphene bandstructure

2015-12-23 Thread Xavier Rocquefelte
Dear Fhokrul
Your structure looks strange to me. The angle is 60° and not 120° and it seems 
that you do not take benefit of the symetry. 
Here is a cif file of graphene based on the graphite structure in which I have 
simply increase the c parameter. 
The structure you are using may explain why you still have a gap (symetry 
problem). 
Best Regards
Xavier

#==

# CRYSTAL DATA

#--

data_VESTA_phase_1

_pd_phase_name 'C'
_cell_length_a 2.45600
_cell_length_b 2.45600
_cell_length_c 15.0
_cell_angle_alpha  90
_cell_angle_beta   90
_cell_angle_gamma  120
_symmetry_space_group_name_H-M 'P 63 m c'
_symmetry_Int_Tables_number    186

loop_
_symmetry_equiv_pos_as_xyz
'x, y, z'
'-y, x-y, z'
'-x+y, -x, z'
'-x, -y, z+1/2'
'y, -x+y, z+1/2'
'x-y, x, z+1/2'
'-y, -x, z'
'-x+y, y, z'
'x, x-y, z'
'y, x, z+1/2'
'x-y, -y, z+1/2'
'-x, -x+y, z+1/2'

loop_
_atom_site_label
_atom_site_occupancy
_atom_site_fract_x
_atom_site_fract_y
_atom_site_fract_z
_atom_site_adp_type
_atom_site_B_iso_or_equiv
_atom_site_type_symbol
C1 1.0 0.00  0.00  0.00 Biso  1.00 C
C2 1.0 0.33  0.67  0.00 Biso  1.00 C

"Islam, Md F" <isl...@uta.edu> a écrit :

> Sorry, in my earlier email, I meant to say with 30 x 30 x 1 mesh, gap 
> is smaller but
> it doesn't close completely.
>
> Thanks,
> Fhokrul
>
>
> 
> From: wien-boun...@zeus.theochem.tuwien.ac.at 
> [wien-boun...@zeus.theochem.tuwien.ac.at] On Behalf Of Islam, Md F 
> [isl...@uta.edu]
> Sent: Wednesday, December 23, 2015 6:22 AM
> To: A Mailing list for WIEN2k users
> Subject: Re: [Wien] Graphene bandstructure
>
> Hi Prof Blaha,
>
>     Here is the structure I am using. I tried to be as precise as 
> possible with position coordinates.
> I think size of the vacuum is sufficiently large so that 
> supercell-supercell interaction is negligible.
> So far what I have got is that with LDA xc if I use 25 x 25 x 1 
> k-mesh there is a gap at the Fermi
> level (which passes through K point) but if I use 30 x 30 x 1 k-mesh, 
> gap closes but DOS is not
> zero at the Fermi level (about 0.001/eV). Please let me know if I am 
> doing anything wrong with
> this calculation.
>
>
> Thanks,
> Fhokrul
>
>
> Graphene
> P LATTICE,NONEQUIV.ATOMS: 2
> MODE OF CALC=RELA unit=bohr
> 4.647800 4.647800 30.00 90.00 90.00 60.00
> ATOM -1: X=0. Y=0. Z=0.5000
>              MULT= 1 ISPLIT= 8
> C             NPT= 781 R0=0.0001 RMT= 1.3200 Z: 6.0
> LOCAL ROT MATRIX:    1.000 0.000 0.000
>                                0.000 1.000 0.000
>                                0.000 0.000 1.000
> ATOM -2: X=0.6667 Y=0.6667 Z=0.5000
>              MULT= 1 ISPLIT= 8
> C             NPT= 781 R0=0.0001 RMT= 1.3200 Z: 6.0
> LOCAL ROT MATRIX:     1.000 0.000 0.000
>                                 0.000 1.000 0.000
>                                 0.000 0.000 1.000
> 12 NUMBER OF SYMMETRY OPERATIONS
> -1-1 0 0.
> 0 1 0 0.
> 0 0-1 0.
> 1
> -1-1 0 0.
> 0 1 0 0.
> 0 0 1 0.
> 2
> -1-1 0 0.
> 1 0 0 0.
> 0 0-1 0.
> 3
> -1-1 0 0.
> 1 0 0 0.
> 0 0 1 0.
> 4
> 0 1 0 0.
> -1-1 0 0.
> 0 0-1 0.
> 5
> 0 1 0 0.
> -1-1 0 0.
> 0 0 1 0.
> 6
> 0 1 0 0.
> 1 0 0 0.
> 0 0-1 0.
> 7
> 0 1 0 0.
> 1 0 0 0.
> 0 0 1 0.
> 8
> 1 0 0 0.
> -1-1 0 0.
> 0 0-1 0.
> 9
> 1 0 0 0.
> -1-1 0 0.
> 0 0 1 0.
> 10
> 1 0 0 0.
> 0 1 0 0.
> 0 0-1 0.
> 11
> 1 0 0 0.
> 0 1 0 0.
> 0 0 1 0.0000
> 12
>
>
>
>
> 
> From: wien-boun...@zeus.theochem.tuwien.ac.at 
> [wien-boun...@zeus.theochem.tuwien.ac.at] On Behalf Of Peter Blaha 
> [pbl...@theochem.tuwien.ac.at]
> Sent: Tuesday, December 22, 2015 3:29 PM
> To: A Mailing list for WIEN2k users
> Subject: Re: [Wien] Graphene bandstructure
>
> The two eigenvalues at K must be identical by symmetry.
>
> If you have a splitting of some meV it means that your structure is
> slightly wrong.
>
> Typical errors: p

Re: [Wien] Graphene bandstructure

2015-12-23 Thread Peter Blaha

a) As expected, something is wrong with your structure.

It should be a hexagonal lattice   (H  and not P) and the angle gamma 
should be 120 and not 60, and also the positions need to be changed then.


With an "H" lattice, wien2k keeps the symmetry properly and is less 
affected by rounding errors.


b) And secondly, you did not answer, how you got the "gap" (from 
scf-file, output1 or bandstructure or DOS ???)


Forget DOS (there is a smearing parameter set by default !)

when you use a H lattice and meshes which can be divided by 3 (because K 
has 1/3,1/3,0 coordinates and only with  a mesh like 3 3 1, 6 6 1, 9 9 
1, ...   the "K"-point is in the mesh), you can use :GAP from scf, 
otherwise NOT.  (best is to use a mesh conpatible with 2 and 3, so 6,6,1 
or 12,12,1 ..., because this includes also the M point.




On 12/23/2015 01:22 PM, Islam, Md F wrote:

Hi Prof Blaha,

 Here is the structure I am using. I tried to be as precise as possible 
with position coordinates.
I think size of the vacuum is sufficiently large so that supercell-supercell 
interaction is negligible.
So far what I have got is that with LDA xc if I use 25 x 25 x 1 k-mesh there is 
a gap at the Fermi
level (which passes through K point) but if I use 30 x 30 x 1 k-mesh, gap 
closes but DOS is not
zero at the Fermi level (about 0.001/eV). Please let me know if I am doing 
anything wrong with
this calculation.


Thanks,
Fhokrul


Graphene
P LATTICE,NONEQUIV.ATOMS: 2
MODE OF CALC=RELA unit=bohr
4.647800 4.647800 30.00 90.00 90.00 60.00
ATOM -1: X=0. Y=0. Z=0.5000
  MULT= 1 ISPLIT= 8
C NPT= 781 R0=0.0001 RMT= 1.3200 Z: 6.0
LOCAL ROT MATRIX:1.000 0.000 0.000
0.000 1.000 0.000
0.000 0.000 1.000
ATOM -2: X=0.6667 Y=0.6667 Z=0.5000
  MULT= 1 ISPLIT= 8
C NPT= 781 R0=0.0001 RMT= 1.3200 Z: 6.0
LOCAL ROT MATRIX: 1.000 0.000 0.000
 0.000 1.000 0.000
 0.000 0.000 1.000
12 NUMBER OF SYMMETRY OPERATIONS
-1-1 0 0.
0 1 0 0.
0 0-1 0.
1
-1-1 0 0.
0 1 0 0.
0 0 1 0.
2
-1-1 0 0.
1 0 0 0.
0 0-1 0.
3
-1-1 0 0.
1 0 0 0.
0 0 1 0.
4
0 1 0 0.
-1-1 0 0.
0 0-1 0.
5
0 1 0 0.
-1-1 0 0.
0 0 1 0.
6
0 1 0 0.
1 0 0 0.
0 0-1 0.
7
0 1 0 0.
1 0 0 0.
0 0 1 0.
8
1 0 0 0.
-1-1 0 0.
0 0-1 0.
9
1 0 0 0.
-1-1 0 0.
0 0 1 0.
10
1 0 0 0.
0 1 0 0.
0 0-1 0.
11
1 0 0 0.
0 1 0 0.
0 0 1 0.
12





From: wien-boun...@zeus.theochem.tuwien.ac.at 
[wien-boun...@zeus.theochem.tuwien.ac.at] On Behalf Of Peter Blaha 
[pbl...@theochem.tuwien.ac.at]
Sent: Tuesday, December 22, 2015 3:29 PM
To: A Mailing list for WIEN2k users
Subject: Re: [Wien] Graphene bandstructure

The two eigenvalues at K must be identical by symmetry.

If you have a splitting of some meV it means that your structure is
slightly wrong.

Typical errors: positions of 1/3 and 2/3 must be given in full precision.
   0.   is NOT 1/3

Am 22.12.2015 um 20:31 schrieb Islam, Md F:

Hi Prof Blaha,

  I have got the gap from plotting bandstructure as well as DOS 
calculations.
I can see the linear dispersion at the K point just like the way it is suppose 
to be
when I plot all the bands in eV range. But if I zoom in at the K point in meV 
range,
I can see the gap.

 I don't think there is anything wrong with the structure. I did check all 
bond lengths,
angles before I ran the calculations and they are correct. I suspect I may have 
to adjust
parameters. I started to see some difference with LDA xc functional with larger 
k mesh.


Thanks,
Fhokrul





From: wien-boun...@zeus.theochem.tuwien.ac.at 
[wien-boun...@zeus.theochem.tuwien.ac.at] On Behalf Of Peter Blaha 
[pbl...@theochem.tuwien.ac.at]
Sent: Tuesday, December 22, 2015 11:35 AM
To: A Mailing list for WIEN2k users
Subject: Re: [Wien] Graphene bandstructure

Graphene is metallic by "symmetry", i.e. EF is at a 2-fold eigenvalue at
the K-point and bands cross with a linear dispersion.

   From where do you know that graphene has a gap in your calculations ??

   From :gap in the scf file or from plotting the bandstructure or ...

It the state at K is not degenerate, you have the wrong symmetry and are
not doing graphene.

Am 22.12.2015 um 16:51 schrieb Islam, Md F:

Hi,

I am trying to do a bandstructure calculation of graphene to check if I 
can
reproduce results discussed in literature (I am using a unit cell of 2 atoms).
With spin-orbit coup

Re: [Wien] Graphene bandstructure

2015-12-22 Thread Islam, Md F
Hi Prof Blaha,

I have got the gap from plotting bandstructure as well as DOS calculations.
I can see the linear dispersion at the K point just like the way it is suppose 
to be
when I plot all the bands in eV range. But if I zoom in at the K point in meV 
range,
I can see the gap.  

   I don't think there is anything wrong with the structure. I did check all 
bond lengths,
angles before I ran the calculations and they are correct. I suspect I may have 
to adjust 
parameters. I started to see some difference with LDA xc functional with larger 
k mesh.


Thanks,
Fhokrul  
 




From: wien-boun...@zeus.theochem.tuwien.ac.at 
[wien-boun...@zeus.theochem.tuwien.ac.at] On Behalf Of Peter Blaha 
[pbl...@theochem.tuwien.ac.at]
Sent: Tuesday, December 22, 2015 11:35 AM
To: A Mailing list for WIEN2k users
Subject: Re: [Wien] Graphene bandstructure

Graphene is metallic by "symmetry", i.e. EF is at a 2-fold eigenvalue at
the K-point and bands cross with a linear dispersion.

 From where do you know that graphene has a gap in your calculations ??

 From :gap in the scf file or from plotting the bandstructure or ...

It the state at K is not degenerate, you have the wrong symmetry and are
not doing graphene.

Am 22.12.2015 um 16:51 schrieb Islam, Md F:
> Hi,
>
>   I am trying to do a bandstructure calculation of graphene to check if I 
> can
> reproduce results discussed in literature (I am using a unit cell of 2 atoms).
> With spin-orbit coupling, there should be a gap of the order of few micro-eV
> and without spin-orbit, there should not be any gap at Dirac point. But I am
> getting a gap of meV even without spin-orbit. I tried both GGA and LDA with
> very dense mesh but the gap does not close. So I am wondering if anyone
> have any suggestion about how to do it in Wien2k.
>
>
> Thanks,
> Fhokrul
> ___
> Wien mailing list
> Wien@zeus.theochem.tuwien.ac.at
> http://zeus.theochem.tuwien.ac.at/mailman/listinfo/wien
> SEARCH the MAILING-LIST at:  
> http://www.mail-archive.com/wien@zeus.theochem.tuwien.ac.at/index.html
>

--
--
Peter BLAHA, Inst.f. Materials Chemistry, TU Vienna, A-1060 Vienna
Phone: +43-1-58801-165300 FAX: +43-1-58801-165982
Email: bl...@theochem.tuwien.ac.atWIEN2k: http://www.wien2k.at
WWW:   http://www.imc.tuwien.ac.at/staff/tc_group_e.php
--
___
Wien mailing list
Wien@zeus.theochem.tuwien.ac.at
http://zeus.theochem.tuwien.ac.at/mailman/listinfo/wien
SEARCH the MAILING-LIST at:  
http://www.mail-archive.com/wien@zeus.theochem.tuwien.ac.at/index.html
___
Wien mailing list
Wien@zeus.theochem.tuwien.ac.at
http://zeus.theochem.tuwien.ac.at/mailman/listinfo/wien
SEARCH the MAILING-LIST at:  
http://www.mail-archive.com/wien@zeus.theochem.tuwien.ac.at/index.html


Re: [Wien] Graphene bandstructure

2015-12-22 Thread Peter Blaha

The two eigenvalues at K must be identical by symmetry.

If you have a splitting of some meV it means that your structure is 
slightly wrong.


Typical errors: positions of 1/3 and 2/3 must be given in full precision.
 0.   is NOT 1/3

Am 22.12.2015 um 20:31 schrieb Islam, Md F:

Hi Prof Blaha,

 I have got the gap from plotting bandstructure as well as DOS calculations.
I can see the linear dispersion at the K point just like the way it is suppose 
to be
when I plot all the bands in eV range. But if I zoom in at the K point in meV 
range,
I can see the gap.

I don't think there is anything wrong with the structure. I did check all 
bond lengths,
angles before I ran the calculations and they are correct. I suspect I may have 
to adjust
parameters. I started to see some difference with LDA xc functional with larger 
k mesh.


Thanks,
Fhokrul





From: wien-boun...@zeus.theochem.tuwien.ac.at 
[wien-boun...@zeus.theochem.tuwien.ac.at] On Behalf Of Peter Blaha 
[pbl...@theochem.tuwien.ac.at]
Sent: Tuesday, December 22, 2015 11:35 AM
To: A Mailing list for WIEN2k users
Subject: Re: [Wien] Graphene bandstructure

Graphene is metallic by "symmetry", i.e. EF is at a 2-fold eigenvalue at
the K-point and bands cross with a linear dispersion.

  From where do you know that graphene has a gap in your calculations ??

  From :gap in the scf file or from plotting the bandstructure or ...

It the state at K is not degenerate, you have the wrong symmetry and are
not doing graphene.

Am 22.12.2015 um 16:51 schrieb Islam, Md F:

Hi,

   I am trying to do a bandstructure calculation of graphene to check if I 
can
reproduce results discussed in literature (I am using a unit cell of 2 atoms).
With spin-orbit coupling, there should be a gap of the order of few micro-eV
and without spin-orbit, there should not be any gap at Dirac point. But I am
getting a gap of meV even without spin-orbit. I tried both GGA and LDA with
very dense mesh but the gap does not close. So I am wondering if anyone
have any suggestion about how to do it in Wien2k.


Thanks,
Fhokrul
___
Wien mailing list
Wien@zeus.theochem.tuwien.ac.at
http://zeus.theochem.tuwien.ac.at/mailman/listinfo/wien
SEARCH the MAILING-LIST at:  
http://www.mail-archive.com/wien@zeus.theochem.tuwien.ac.at/index.html



--
--
Peter BLAHA, Inst.f. Materials Chemistry, TU Vienna, A-1060 Vienna
Phone: +43-1-58801-165300 FAX: +43-1-58801-165982
Email: bl...@theochem.tuwien.ac.atWIEN2k: http://www.wien2k.at
WWW:   http://www.imc.tuwien.ac.at/staff/tc_group_e.php
--
___
Wien mailing list
Wien@zeus.theochem.tuwien.ac.at
http://zeus.theochem.tuwien.ac.at/mailman/listinfo/wien
SEARCH the MAILING-LIST at:  
http://www.mail-archive.com/wien@zeus.theochem.tuwien.ac.at/index.html
___
Wien mailing list
Wien@zeus.theochem.tuwien.ac.at
http://zeus.theochem.tuwien.ac.at/mailman/listinfo/wien
SEARCH the MAILING-LIST at:  
http://www.mail-archive.com/wien@zeus.theochem.tuwien.ac.at/index.html



--
--
Peter BLAHA, Inst.f. Materials Chemistry, TU Vienna, A-1060 Vienna
Phone: +43-1-58801-165300 FAX: +43-1-58801-165982
Email: bl...@theochem.tuwien.ac.atWIEN2k: http://www.wien2k.at
WWW:   http://www.imc.tuwien.ac.at/staff/tc_group_e.php
--
___
Wien mailing list
Wien@zeus.theochem.tuwien.ac.at
http://zeus.theochem.tuwien.ac.at/mailman/listinfo/wien
SEARCH the MAILING-LIST at:  
http://www.mail-archive.com/wien@zeus.theochem.tuwien.ac.at/index.html


Re: [Wien] Graphene bandstructure

2015-12-22 Thread Hajar Nejati
I think that RKmax (case.in1) is one of the important computational parameters 
in an accurate describing of the electronic structure of graphene. I think that 
RKmax equal to 8.0 leads to a better band structure result for graphene.
All the best
 

  From: "Islam, Md F" 
 To: A Mailing list for WIEN2k users  
 Sent: Tuesday, December 22, 2015 7:21 PM
 Subject: [Wien] Graphene bandstructure
   
Hi,

    I am trying to do a bandstructure calculation of graphene to check if I can
reproduce results discussed in literature (I am using a unit cell of 2 atoms). 
With spin-orbit coupling, there should be a gap of the order of few micro-eV
and without spin-orbit, there should not be any gap at Dirac point. But I am 
getting a gap of meV even without spin-orbit. I tried both GGA and LDA with 
very dense mesh but the gap does not close. So I am wondering if anyone 
have any suggestion about how to do it in Wien2k.


Thanks,
Fhokrul
___
Wien mailing list
Wien@zeus.theochem.tuwien.ac.at
http://zeus.theochem.tuwien.ac.at/mailman/listinfo/wien
SEARCH the MAILING-LIST at:  
http://www.mail-archive.com/wien@zeus.theochem.tuwien.ac.at/index.html


  ___
Wien mailing list
Wien@zeus.theochem.tuwien.ac.at
http://zeus.theochem.tuwien.ac.at/mailman/listinfo/wien
SEARCH the MAILING-LIST at:  
http://www.mail-archive.com/wien@zeus.theochem.tuwien.ac.at/index.html


Re: [Wien] Graphene bandstructure

2015-12-22 Thread Islam, Md F
Thanks, for your reply. I have used a vacuum of 30 bohr but I can 
try with larger vacuum to check if it makes any difference.


Fhokrul



From: wien-boun...@zeus.theochem.tuwien.ac.at 
[wien-boun...@zeus.theochem.tuwien.ac.at] On Behalf Of 
t...@theochem.tuwien.ac.at [t...@theochem.tuwien.ac.at]
Sent: Tuesday, December 22, 2015 10:20 AM
To: A Mailing list for WIEN2k users
Subject: Re: [Wien] Graphene bandstructure

Hi,

For graphene, you need to add vacuum in the z-direction in order to
avoid interactions between the periodically repeated monolayers.
Maybe the vacuum that you used is not large enough.

F. Tran

On Tue, 22 Dec 2015, Islam, Md F wrote:

> Hi,
>
> I am trying to do a bandstructure calculation of graphene to check if I 
> can
> reproduce results discussed in literature (I am using a unit cell of 2 atoms).
> With spin-orbit coupling, there should be a gap of the order of few micro-eV
> and without spin-orbit, there should not be any gap at Dirac point. But I am
> getting a gap of meV even without spin-orbit. I tried both GGA and LDA with
> very dense mesh but the gap does not close. So I am wondering if anyone
> have any suggestion about how to do it in Wien2k.
>
>
> Thanks,
> Fhokrul
> ___
> Wien mailing list
> Wien@zeus.theochem.tuwien.ac.at
> http://zeus.theochem.tuwien.ac.at/mailman/listinfo/wien
> SEARCH the MAILING-LIST at:  
> http://www.mail-archive.com/wien@zeus.theochem.tuwien.ac.at/index.html
>
___
Wien mailing list
Wien@zeus.theochem.tuwien.ac.at
http://zeus.theochem.tuwien.ac.at/mailman/listinfo/wien
SEARCH the MAILING-LIST at:  
http://www.mail-archive.com/wien@zeus.theochem.tuwien.ac.at/index.html
___
Wien mailing list
Wien@zeus.theochem.tuwien.ac.at
http://zeus.theochem.tuwien.ac.at/mailman/listinfo/wien
SEARCH the MAILING-LIST at:  
http://www.mail-archive.com/wien@zeus.theochem.tuwien.ac.at/index.html


Re: [Wien] Graphene bandstructure

2015-12-22 Thread tran

Hi,

For graphene, you need to add vacuum in the z-direction in order to
avoid interactions between the periodically repeated monolayers.
Maybe the vacuum that you used is not large enough.

F. Tran

On Tue, 22 Dec 2015, Islam, Md F wrote:


Hi,

I am trying to do a bandstructure calculation of graphene to check if I can
reproduce results discussed in literature (I am using a unit cell of 2 atoms).
With spin-orbit coupling, there should be a gap of the order of few micro-eV
and without spin-orbit, there should not be any gap at Dirac point. But I am
getting a gap of meV even without spin-orbit. I tried both GGA and LDA with
very dense mesh but the gap does not close. So I am wondering if anyone
have any suggestion about how to do it in Wien2k.


Thanks,
Fhokrul
___
Wien mailing list
Wien@zeus.theochem.tuwien.ac.at
http://zeus.theochem.tuwien.ac.at/mailman/listinfo/wien
SEARCH the MAILING-LIST at:  
http://www.mail-archive.com/wien@zeus.theochem.tuwien.ac.at/index.html


___
Wien mailing list
Wien@zeus.theochem.tuwien.ac.at
http://zeus.theochem.tuwien.ac.at/mailman/listinfo/wien
SEARCH the MAILING-LIST at:  
http://www.mail-archive.com/wien@zeus.theochem.tuwien.ac.at/index.html


Re: [Wien] Graphene bandstructure

2015-12-22 Thread Peter Blaha
Graphene is metallic by "symmetry", i.e. EF is at a 2-fold eigenvalue at 
the K-point and bands cross with a linear dispersion.


From where do you know that graphene has a gap in your calculations ??

From :gap in the scf file or from plotting the bandstructure or ...

It the state at K is not degenerate, you have the wrong symmetry and are 
not doing graphene.


Am 22.12.2015 um 16:51 schrieb Islam, Md F:

Hi,

  I am trying to do a bandstructure calculation of graphene to check if I 
can
reproduce results discussed in literature (I am using a unit cell of 2 atoms).
With spin-orbit coupling, there should be a gap of the order of few micro-eV
and without spin-orbit, there should not be any gap at Dirac point. But I am
getting a gap of meV even without spin-orbit. I tried both GGA and LDA with
very dense mesh but the gap does not close. So I am wondering if anyone
have any suggestion about how to do it in Wien2k.


Thanks,
Fhokrul
___
Wien mailing list
Wien@zeus.theochem.tuwien.ac.at
http://zeus.theochem.tuwien.ac.at/mailman/listinfo/wien
SEARCH the MAILING-LIST at:  
http://www.mail-archive.com/wien@zeus.theochem.tuwien.ac.at/index.html



--
--
Peter BLAHA, Inst.f. Materials Chemistry, TU Vienna, A-1060 Vienna
Phone: +43-1-58801-165300 FAX: +43-1-58801-165982
Email: bl...@theochem.tuwien.ac.atWIEN2k: http://www.wien2k.at
WWW:   http://www.imc.tuwien.ac.at/staff/tc_group_e.php
--
___
Wien mailing list
Wien@zeus.theochem.tuwien.ac.at
http://zeus.theochem.tuwien.ac.at/mailman/listinfo/wien
SEARCH the MAILING-LIST at:  
http://www.mail-archive.com/wien@zeus.theochem.tuwien.ac.at/index.html


Re: [Wien] Graphene bandstructure

2015-12-22 Thread Michael Sluydts
While I haven't done any graphene calculations, one of the typical 
issues in bandgap discrepancies is also the existence of strain. Ensure 
your lateral lattice parameters are optimized using your current 
functional so that you're certain you are looking at the band structure 
of the energetic minimum. Of course don't optimize the vacuum or you'll 
end up with graphite...


Best regards,

Michael Sluydts

Op 22/12/2015 om 17:43 schreef Islam, Md F:

Thanks, for your reply. I have used a vacuum of 30 bohr but I can
try with larger vacuum to check if it makes any difference.


Fhokrul



From: wien-boun...@zeus.theochem.tuwien.ac.at 
[wien-boun...@zeus.theochem.tuwien.ac.at] On Behalf Of 
t...@theochem.tuwien.ac.at [t...@theochem.tuwien.ac.at]
Sent: Tuesday, December 22, 2015 10:20 AM
To: A Mailing list for WIEN2k users
Subject: Re: [Wien] Graphene bandstructure

Hi,

For graphene, you need to add vacuum in the z-direction in order to
avoid interactions between the periodically repeated monolayers.
Maybe the vacuum that you used is not large enough.

F. Tran

On Tue, 22 Dec 2015, Islam, Md F wrote:


Hi,

 I am trying to do a bandstructure calculation of graphene to check if I can
reproduce results discussed in literature (I am using a unit cell of 2 atoms).
With spin-orbit coupling, there should be a gap of the order of few micro-eV
and without spin-orbit, there should not be any gap at Dirac point. But I am
getting a gap of meV even without spin-orbit. I tried both GGA and LDA with
very dense mesh but the gap does not close. So I am wondering if anyone
have any suggestion about how to do it in Wien2k.


Thanks,
Fhokrul
___
Wien mailing list
Wien@zeus.theochem.tuwien.ac.at
http://zeus.theochem.tuwien.ac.at/mailman/listinfo/wien
SEARCH the MAILING-LIST at:  
http://www.mail-archive.com/wien@zeus.theochem.tuwien.ac.at/index.html


___
Wien mailing list
Wien@zeus.theochem.tuwien.ac.at
http://zeus.theochem.tuwien.ac.at/mailman/listinfo/wien
SEARCH the MAILING-LIST at:  
http://www.mail-archive.com/wien@zeus.theochem.tuwien.ac.at/index.html
___
Wien mailing list
Wien@zeus.theochem.tuwien.ac.at
http://zeus.theochem.tuwien.ac.at/mailman/listinfo/wien
SEARCH the MAILING-LIST at:  
http://www.mail-archive.com/wien@zeus.theochem.tuwien.ac.at/index.html



--
ir. Michael Sluydts
Center for Molecular Modeling
Ghent University
Technologiepark 903
9052 Zwijnaarde, Belgium
tel. +32 (0)9 264 66 19
https://molmod.ugent.be

___
Wien mailing list
Wien@zeus.theochem.tuwien.ac.at
http://zeus.theochem.tuwien.ac.at/mailman/listinfo/wien
SEARCH the MAILING-LIST at:  
http://www.mail-archive.com/wien@zeus.theochem.tuwien.ac.at/index.html


Re: [Wien] Graphene bandstructure

2015-12-22 Thread Islam, Md F
Hi Michael,

Thanks for your comments. You may be right. I haven't relaxed lateral
lattice parameters, just used the experimental values. 

Best regards,
Fhokrul

 


From: wien-boun...@zeus.theochem.tuwien.ac.at 
[wien-boun...@zeus.theochem.tuwien.ac.at] On Behalf Of Michael Sluydts 
[michael.sluy...@ugent.be]
Sent: Tuesday, December 22, 2015 11:10 AM
To: A Mailing list for WIEN2k users
Subject: Re: [Wien] Graphene bandstructure

While I haven't done any graphene calculations, one of the typical
issues in bandgap discrepancies is also the existence of strain. Ensure
your lateral lattice parameters are optimized using your current
functional so that you're certain you are looking at the band structure
of the energetic minimum. Of course don't optimize the vacuum or you'll
end up with graphite...

Best regards,

Michael Sluydts

Op 22/12/2015 om 17:43 schreef Islam, Md F:
> Thanks, for your reply. I have used a vacuum of 30 bohr but I can
> try with larger vacuum to check if it makes any difference.
>
>
> Fhokrul
>
>
> 
> From: wien-boun...@zeus.theochem.tuwien.ac.at 
> [wien-boun...@zeus.theochem.tuwien.ac.at] On Behalf Of 
> t...@theochem.tuwien.ac.at [t...@theochem.tuwien.ac.at]
> Sent: Tuesday, December 22, 2015 10:20 AM
> To: A Mailing list for WIEN2k users
> Subject: Re: [Wien] Graphene bandstructure
>
> Hi,
>
> For graphene, you need to add vacuum in the z-direction in order to
> avoid interactions between the periodically repeated monolayers.
> Maybe the vacuum that you used is not large enough.
>
> F. Tran
>
> On Tue, 22 Dec 2015, Islam, Md F wrote:
>
>> Hi,
>>
>>  I am trying to do a bandstructure calculation of graphene to check if I 
>> can
>> reproduce results discussed in literature (I am using a unit cell of 2 
>> atoms).
>> With spin-orbit coupling, there should be a gap of the order of few micro-eV
>> and without spin-orbit, there should not be any gap at Dirac point. But I am
>> getting a gap of meV even without spin-orbit. I tried both GGA and LDA with
>> very dense mesh but the gap does not close. So I am wondering if anyone
>> have any suggestion about how to do it in Wien2k.
>>
>>
>> Thanks,
>> Fhokrul
>> ___
>> Wien mailing list
>> Wien@zeus.theochem.tuwien.ac.at
>> http://zeus.theochem.tuwien.ac.at/mailman/listinfo/wien
>> SEARCH the MAILING-LIST at:  
>> http://www.mail-archive.com/wien@zeus.theochem.tuwien.ac.at/index.html
>>
> ___
> Wien mailing list
> Wien@zeus.theochem.tuwien.ac.at
> http://zeus.theochem.tuwien.ac.at/mailman/listinfo/wien
> SEARCH the MAILING-LIST at:  
> http://www.mail-archive.com/wien@zeus.theochem.tuwien.ac.at/index.html
> ___
> Wien mailing list
> Wien@zeus.theochem.tuwien.ac.at
> http://zeus.theochem.tuwien.ac.at/mailman/listinfo/wien
> SEARCH the MAILING-LIST at:  
> http://www.mail-archive.com/wien@zeus.theochem.tuwien.ac.at/index.html


--
ir. Michael Sluydts
Center for Molecular Modeling
Ghent University
Technologiepark 903
9052 Zwijnaarde, Belgium
tel. +32 (0)9 264 66 19
https://molmod.ugent.be

___
Wien mailing list
Wien@zeus.theochem.tuwien.ac.at
http://zeus.theochem.tuwien.ac.at/mailman/listinfo/wien
SEARCH the MAILING-LIST at:  
http://www.mail-archive.com/wien@zeus.theochem.tuwien.ac.at/index.html
___
Wien mailing list
Wien@zeus.theochem.tuwien.ac.at
http://zeus.theochem.tuwien.ac.at/mailman/listinfo/wien
SEARCH the MAILING-LIST at:  
http://www.mail-archive.com/wien@zeus.theochem.tuwien.ac.at/index.html


Re: [Wien] Graphene bandstructure

2015-12-22 Thread Islam, Md F
Hi,

   Thanks for your suggestion. I have checked up to RKmax=9 but the gap
didn't close. But I was using GGA xc functional. I will try with LDA if it 
makes 
any difference. I read in some paper, LDA is supposed to be used for these 
calculations.  


Regards,
Fhokrul




From: wien-boun...@zeus.theochem.tuwien.ac.at 
[wien-boun...@zeus.theochem.tuwien.ac.at] On Behalf Of Hajar Nejati 
[hajar.nejatip...@yahoo.com]
Sent: Tuesday, December 22, 2015 11:46 AM
To: A Mailing list for WIEN2k users
Subject: Re: [Wien] Graphene bandstructure

I think that RKmax (case.in1) is one of the important computational parameters 
in an accurate describing of the electronic structure of graphene. I think that 
RKmax equal to 8.0 leads to a better band structure result for graphene.

All the best




From: "Islam, Md F" <isl...@uta.edu>
To: A Mailing list for WIEN2k users <wien@zeus.theochem.tuwien.ac.at>
Sent: Tuesday, December 22, 2015 7:21 PM
Subject: [Wien] Graphene bandstructure

Hi,

I am trying to do a bandstructure calculation of graphene to check if I can
reproduce results discussed in literature (I am using a unit cell of 2 atoms).
With spin-orbit coupling, there should be a gap of the order of few micro-eV
and without spin-orbit, there should not be any gap at Dirac point. But I am
getting a gap of meV even without spin-orbit. I tried both GGA and LDA with
very dense mesh but the gap does not close. So I am wondering if anyone
have any suggestion about how to do it in Wien2k.


Thanks,
Fhokrul

___
Wien mailing list
Wien@zeus.theochem.tuwien.ac.at<mailto:Wien@zeus.theochem.tuwien.ac.at>
http://zeus.theochem.tuwien.ac.at/mailman/listinfo/wien
SEARCH the MAILING-LIST at:  
http://www.mail-archive.com/wien@zeus.theochem.tuwien.ac.at/index.html


___
Wien mailing list
Wien@zeus.theochem.tuwien.ac.at
http://zeus.theochem.tuwien.ac.at/mailman/listinfo/wien
SEARCH the MAILING-LIST at:  
http://www.mail-archive.com/wien@zeus.theochem.tuwien.ac.at/index.html