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RESEARCH PRODUCT

First principles calculations of SrZrO3 bulk and ZrO2-terminated (001) surface F centers

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Abstract Using a supercell model and B3PW hybrid exchange-correlation functional in the framework of the density functional theory (DFT), as it is implemented in the CRYSTAL computer code, we performed ab initio calculations for the F -center located in the SrZrO 3 bulk and on the ZrO 2 -terminated (001) surface. According to the results of performed relaxation of atoms around the defect, two nearest Zr and four Sr atoms are repulsed, but all oxygen atoms are attracted towards both, the bulk and (001) surface F -center. The displacement magnitudes of atoms surrounding the bulk F -center are smaller than around the (001) surface F -center. The B3PW calculated SrZrO 3 bulk optical band gap (5.00 eV) is in a fair agreement with the experimental value of 5.6 eV. The ZrO 2 -terminated (001) surface optical band gap (4.63 eV) is smaller in regard to the bulk value. The bulk and (001) surface F -center bands in SrZrO 3 , calculated using 3 × 3 × 3 and 3 × 3 × 1 times expanded supercells, are located 1.12 and 0.93 eV under the conduction band bottom. The O vacancy in the SrZrO 3 bulk attracts 1.25 e , and even less, only 1.10 e on the ZrO 2 -terminated (001) surface. Performed calculations reveal significant enhancement of the chemical bond covalency among the SrZrO 3 bulk F -center and its nearest Zr atoms of 0.244 e in comparison with the ideal SrZrO 3 perovskite Zr O chemical bond covalency of 0.100 e . Our detected defect formation energy for the F -center located on the ZrO 2 -terminated (001) surface 7.52 eV is somewhat smaller than in the SrZrO 3 bulk 7.55 eV. Our calculated formation energy difference may trigger the segregation of the F -center from the SrZrO 3 bulk towards the ZrO 2 -terminated (001) surface.