Dear Izaak Wurtzite ZnO is a very (VERY) nasty semiconductor... I find a PBE band gap of 0.8 eV, in agreement with previous investigations. Hybrid functionals, as HSE with alpha=0.25, do not heal the whole of it; you find something around 2.2 eV (If you are interested, I can cite several papers). This is due to the very narrow Zn 3d band which is very strongly affected by delocalisation (aka self- interaction) errors. The conduction band minimum (CBM) appears as a tiny feature (the 0.5 eV one, I suppose) in your DOS because the CB is sharply peaked around Gamma, so that even if your calculation is well converged wrt energy, forces, stress, ..., you do not achieve a good sampling around the CBM. How can you cure it? It depends on your final purpose, which I suppose is not the band structure of a 4-atoms cell... You mat write directly to me if you are going to look for further advice. HTH
Giuseppe On Thursday 17 May 2012 23:43:45 Izaak Williamson wrote: > Hello all, > > I am trying to calculate the electronic bandgap for wurtzite ZnO using > the attached plot of DoS (E), where the Fermi level is represented by a > vertical > > dashed-line and EV represents the valence band maximum. > > My question is, should I use EC1 or EC2 as my conduction band minimum? > If I use EC1, the bandgap is ~0.5eV but if I consider those states at > that point negligible and use EC2 then the bandgap is ~1.5eV. (NOTE: > > the experimental bandgap is 3.36eV.) > > Thanks for the help. -- ******************************************************** - Article premier - Les hommes naissent et demeurent libres et ?gaux en droits. Les distinctions sociales ne peuvent ?tre fond?es que sur l'utilit? commune - Article 2 - Le but de toute association politique est la conservation des droits naturels et imprescriptibles de l'homme. Ces droits sont la libert?, la propri?t?, la s?ret? et la r?sistance ? l'oppression. ******************************************************** Giuseppe Mattioli CNR - ISTITUTO DI STRUTTURA DELLA MATERIA v. Salaria Km 29,300 - C.P. 10 I 00015 - Monterotondo Stazione (RM) Tel + 39 06 90672836 - Fax +39 06 90672316 E-mail: <giuseppe.mattioli at ism.cnr.it>
