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
bulk.inorb
Description: Binary data
bulk.in1
Description: Binary data
supercell.in1
Description: Binary data
bulk.in2c
Description: Binary data
bulk.struct
Description: Binary data
supercell.in2c
Description: Binary data
supercell.struct
Description: Binary data
supercell.inorb
Description: Binary data
_______________________________________________ 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
