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 30.000000 90.000000 90.000000 60.000000 ATOM -1: X=0.00000000 Y=0.00000000 Z=0.50000000 MULT= 1 ISPLIT= 8 C NPT= 781 R0=0.00010000 RMT= 1.3200 Z: 6.0 LOCAL ROT MATRIX: 1.0000000 0.0000000 0.0000000 0.0000000 1.0000000 0.0000000 0.0000000 0.0000000 1.0000000 ATOM -2: X=0.66666667 Y=0.66666667 Z=0.50000000 MULT= 1 ISPLIT= 8 C NPT= 781 R0=0.00010000 RMT= 1.3200 Z: 6.0 LOCAL ROT MATRIX: 1.0000000 0.0000000 0.0000000 0.0000000 1.0000000 0.0000000 0.0000000 0.0000000 1.0000000 12 NUMBER OF SYMMETRY OPERATIONS -1-1 0 0.00000000 0 1 0 0.00000000 0 0-1 0.00000000 1 -1-1 0 0.00000000 0 1 0 0.00000000 0 0 1 0.00000000 2 -1-1 0 0.00000000 1 0 0 0.00000000 0 0-1 0.00000000 3 -1-1 0 0.00000000 1 0 0 0.00000000 0 0 1 0.00000000 4 0 1 0 0.00000000 -1-1 0 0.00000000 0 0-1 0.00000000 5 0 1 0 0.00000000 -1-1 0 0.00000000 0 0 1 0.00000000 6 0 1 0 0.00000000 1 0 0 0.00000000 0 0-1 0.00000000 7 0 1 0 0.00000000 1 0 0 0.00000000 0 0 1 0.00000000 8 1 0 0 0.00000000 -1-1 0 0.00000000 0 0-1 0.00000000 9 1 0 0 0.00000000 -1-1 0 0.00000000 0 0 1 0.00000000 10 1 0 0 0.00000000 0 1 0 0.00000000 0 0-1 0.00000000 11 1 0 0 0.00000000 0 1 0 0.00000000 0 0 1 0.00000000 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. 0.3333 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.at WIEN2k: 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.at WIEN2k: 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