2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/28858An ab initio LMTO approach and semi-empirical quantum chemical INDO method have been used for supercell calculations of basic point defects - F-type centers and hole polarons bound to cation vacancy - in partly covalent perovskite KNbO3. We predict the existence of both one-site and two-site (molecular) polarons with close absorption energies (~ 1 eV). The relevant experimental data are discussed and interpreted.7 pages with 1 embedded postscript figure; submitted to the proceedings of the 2nd Asian Meeting on FerroelectricsMaterials Sciencetext