Thanks a lot On Wed, Sep 13, 2023 at 8:56 PM Peter Blaha <peter.bl...@tuwien.ac.at> wrote:
> In addition to what Igor said: > > If you want a reasonable gap for the bulk, you can use mBJ+U (with a > small U of a few eV). > > Still, for your cell, you won't get an insulator (also doped Si is > "metallic" and conducting, otherwise a computer would not work ...). > > PS: Draw the DOS and compare with the undoped DOS. Maybe you understand > then better. > > > Am 13.09.2023 um 19:19 schrieb Natalia Andreeva: > > Dear WIEN2k users, > > > > I am calculating the band gap of bulk BaTiO3 using the LDA+U with PBE > > functional. For the values below, the band gap was 2.002 eV (which I > > can explain by the choice of the PBE functional). When I moved to a > > supercell with a defect (oxygen vacancy, supercell dimensions 2x2x1), > > the band gap became 0.0 eV. > > I tried to increase the Hubbard parameter U. For example, for bulk > > calculations with U=1.121 Ry = 15.252 eV, the band gap was 3.391 eV. > > However, running with the same parameters for a supercell with a > > defect gave a calculated value of 0.889 eV. > > I have the following questions: > > 1. Why does the band gap decrease so much when going from bulk to > > supercell with a defect? > > 2. Is it worth changing the PBE functional to another one if the band > > gap for bulk is less than the experimental one? > > 3. If I continue the calculations on PBE+U, how can I improve the values? > > > > With Best Regards, > > Natalia > > > > > > _______________________________________________ > > 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: +43-158801165300 > Email: peter.bl...@tuwien.ac.at > WWW: http://www.imc.tuwien.ac.at WIEN2k: http://www.wien2k.at > ------------------------------------------------------------------------- > > _______________________________________________ > 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 > -- Best Regards, Natalia Andreeva.
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