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: [email protected] [[email protected]] On Behalf Of Peter Blaha [[email protected]] 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 [email protected] http://zeus.theochem.tuwien.ac.at/mailman/listinfo/wien SEARCH the MAILING-LIST at: http://www.mail-archive.com/[email protected]/index.html-- -------------------------------------------------------------------------- Peter BLAHA, Inst.f. Materials Chemistry, TU Vienna, A-1060 Vienna Phone: +43-1-58801-165300 FAX: +43-1-58801-165982 Email: [email protected] WIEN2k: http://www.wien2k.at WWW: http://www.imc.tuwien.ac.at/staff/tc_group_e.php -------------------------------------------------------------------------- _______________________________________________ Wien mailing list [email protected] http://zeus.theochem.tuwien.ac.at/mailman/listinfo/wien SEARCH the MAILING-LIST at: http://www.mail-archive.com/[email protected]/index.html _______________________________________________ Wien mailing list [email protected] http://zeus.theochem.tuwien.ac.at/mailman/listinfo/wien SEARCH the MAILING-LIST at: http://www.mail-archive.com/[email protected]/index.html
-- -------------------------------------------------------------------------- Peter BLAHA, Inst.f. Materials Chemistry, TU Vienna, A-1060 Vienna Phone: +43-1-58801-165300 FAX: +43-1-58801-165982 Email: [email protected] WIEN2k: http://www.wien2k.at WWW: http://www.imc.tuwien.ac.at/staff/tc_group_e.php -------------------------------------------------------------------------- _______________________________________________ Wien mailing list [email protected] http://zeus.theochem.tuwien.ac.at/mailman/listinfo/wien SEARCH the MAILING-LIST at: http://www.mail-archive.com/[email protected]/index.html
