Dear all, I am doing a SCF calculation by Feff8.40 for a model compound PbTiO3. However, the obtained charge transfer deviates far away from its well-known formal oxidation state. According to common electron negativity data, the oxidation state would be: Pb 2+ Ti 4+ O 2- The SCF run gave out charge transfer for those atoms as following: Pb 0.717 Ti 0.181 O -0.300 After I read through the existing threads on charge transfer in this list, I know that transfered charge FEFF gives out is just a portion of general formal oxidation state. Can we undderstand that this is just ionic portion for entire bonding? Such as for oxygen, "-0.300" is ionic bonding, while the rest of valency (-1.700) exists as covalent bonding, which doesn't have apparent charge transfer by definition. Another related question is then: is there any way in FEFF to take into account this "covalence" part? (maybe deriving from overlapping area of mufftin-potential?) I think this may be crucial for a self-consistent analysis of charge disproportionation. Any comments on this would be greatly appreciated. Attached please see"atom.inp" and "feff.inp". Thanks so much! Ying Ying Zou Research associate,Dr. Phys. Physics Department, UWM ***************atoms.inp*********************************** ! This atoms input file was generated by WebAtoms 1.8 (Atoms 3.0beta10) ! Atoms written by and copyright (c) Bruce Ravel, 1998-2001 title = Perovskite: PbTiO3 space = p 4 m m a = 3.9050 b = 3.9050 c = 4.1560 alpha = 90.0 beta = 90.0 gamma = 90.0 core = Ti edge = K rmax = 4.2950 atoms ! elem x y z tag occ. Pb 0.00000 0.00000 0.00000 Pb 1.00000 Ti 0.50000 0.50000 0.53900 Ti 1.00000 O 0.50000 0.50000 0.11400 Oapical 1.00000 O 0.50000 0.00000 0.61700 Oplanar 1.00000 ****************************************************************** ************feff.inp*************************************** * This feff.inp file generated by ATOMS, version 2.50 * ATOMS written by and copyright (c) Bruce Ravel, 1992-1999 * -- * -- * -- * -- * -- * -- * -- * -- * -- * -- * -- * -- * -- * -- * * total mu = 5194.4 cm^-1, delta mu = 761.6 cm^-1 * specific gravity = 7.942, cluster contains 25 atoms. * -- * -- * -- * -- * -- * -- * -- * -- * -- * -- * -- * -- * -- * -- * * mcmaster corrections: 0.00093 ang^2 and 0.165E-05 ang^4 * -- * -- * -- * -- * -- * -- * -- * -- * -- * -- * -- * -- * -- * -- * TITLE Perovskite: PbTiO3 EDGE K S02 1.0 * pot xsph fms paths genfmt ff2chi CONTROL 1 1 1 1 1 1 PRINT 1 0 0 0 0 3 * r_scf [ l_scf n_scf ca ] SCF 3.88586 0 15 0.1 * ixc [ Vr Vi ] EXCHANGE 0 0 0 EXAFS RPATH 7.77172 * kmax [ delta_k delta_e ] *XANES 4.0 0.07 0.5 * r_fms [ l_fms ] *FMS 3.88586 ******** * *RPATH 0.10000 * emin emax resolution *LDOS -20 20 0.1 POTENTIALS * ipot z [ label l_scmt l_fms stoichiometry ] 0 22 Ti -1 -1 0 1 8 O -1 -1 3 2 82 Pb -1 -1 1 3 22 Ti -1 -1 1 ATOMS 0.00000 0.00000 0.00000 0 Ti 0.00000 0.00000 0.00000 -1.76630 1 Oapical 1.76630 1.95250 0.00000 0.32417 1 Oplanar 1.97923 0.00000 -1.95250 0.32417 1 Oplanar 1.97923 -1.95250 0.00000 0.32417 1 Oplanar 1.97923 0.00000 1.95250 0.32417 1 Oplanar 1.97923 0.00000 0.00000 2.38970 1 Oapical 2.38970 -1.95250 -1.95250 1.91592 2 Pb 3.36084 1.95250 -1.95250 1.91592 2 Pb 3.36084 -1.95250 1.95250 1.91592 2 Pb 3.36084 1.95250 1.95250 1.91592 2 Pb 3.36084 1.95250 -1.95250 -2.24008 2 Pb 3.55563 -1.95250 1.95250 -2.24008 2 Pb 3.55563 -1.95250 -1.95250 -2.24008 2 Pb 3.55563 1.95250 1.95250 -2.24008 2 Pb 3.55563 -3.90500 0.00000 0.00000 3 Ti 3.90500 0.00000 3.90500 0.00000 3 Ti 3.90500 3.90500 0.00000 0.00000 3 Ti 3.90500 0.00000 -3.90500 0.00000 3 Ti 3.90500 0.00000 0.00000 4.15600 3 Ti 4.15600 0.00000 0.00000 -4.15600 3 Ti 4.15600 3.90500 0.00000 -1.76630 1 Oapical 4.28589 0.00000 -3.90500 -1.76630 1 Oapical 4.28589 -3.90500 0.00000 -1.76630 1 Oapical 4.28589 0.00000 3.90500 -1.76630 1 Oapical 4.28589 END *******************************************************************