### Re: [Wien] Graphene bandstructure

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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