[Ifeffit] convergence of XANES for STO

Dear all, I have a question regarding the convergence of XANES calculations. I'm currently focusing on the O-K edge of perovskite oxides, in particular SrTiO3 and found that there are still fine-structure changes for large (9.5Å) clusters. Attached is my *.inp file for the 9.5Å cluster and a summary of the XANES for increasing cluster sizes from 6.5Å to 9.5Å. You can see that there are still significant changes as the cluster size is increased from 8.5 to 9.5Å. In particular, I find a double peak feature in the first 5eV after the edge onset, which is not observed experimentally. Do you have any suggestions how to obtain a better convergence? Secondly, if you compare the simulated XANES with experimental results (see attachment: EELS STO.png), I'm not able to match all three main peaks, even by scaling the energy scale. Are the deviations I'm seeing within the accuracy of FEFF or do I need to improve my *.inp file? Best regards, Lena --------------------------------- Lena Fitting Kourkoutis E13 Clark Hall Cornell University Applied and Engineering Physics Ithaca, NY 14853 phone: 607-255-0654 e-mail: lf56@cornell.edu --------------------------------- TITLE SrTiO3 with core hole HOLE 1 1.0 * pot xsph fms paths genfmt ff2chi CONTROL 1 1 1 1 1 1 PRINT 1 0 0 0 0 0 * ixc [ Vr Vi ] EXCHANGE 0 1.4 0.2 * r_scf [ l_scf n_scf ca ] SCF 5.0 0 30 * kmax [ delta_k delta_e ] XANES 4.0 .01 .17 * r_fms l_fms FMS 9.15804 0 * emin emax eimag LDOS -30 20 0.2 RPATH 0.1 POTENTIALS * ipot Z element l_scmt l_fms stoichiometry 0 8 O -1 -1 0.001 1 38 Sr -1 -1 1 2 22 Ti -1 -1 1 3 8 O -1 -1 3 ATOMS * this list contains 285 atoms * x y z ipot tag distance 0.00000 0.00000 0.00000 0 O1 0.00000 0 0.00000 0.00000 1.95250 2 Ti1 1.95250 1 0.00000 0.00000 -1.95250 2 Ti1 1.95250 2 1.95250 0.00000 1.95250 3 O1 2.76125 3 -1.95250 0.00000 1.95250 3 O1 2.76125 4 0.00000 1.95250 1.95250 3 O1 2.76125 5 0.00000 -1.95250 1.95250 3 O1 2.76125 6 1.95250 0.00000 -1.95250 3 O1 2.76125 7 -1.95250 0.00000 -1.95250 3 O1 2.76125 8 0.00000 1.95250 -1.95250 3 O1 2.76125 9 0.00000 -1.95250 -1.95250 3 O1 2.76125 10 1.95250 1.95250 0.00000 1 Sr1 2.76125 11 -1.95250 1.95250 0.00000 1 Sr1 2.76125 12 1.95250 -1.95250 0.00000 1 Sr1 2.76125 13 -1.95250 -1.95250 0.00000 1 Sr1 2.76125 14 3.90500 0.00000 0.00000 3 O1 3.90500 15 -3.90500 0.00000 0.00000 3 O1 3.90500 16 0.00000 3.90500 0.00000 3 O1 3.90500 17 0.00000 -3.90500 0.00000 3 O1 3.90500 18 0.00000 0.00000 3.90500 3 O1 3.90500 19 0.00000 0.00000 -3.90500 3 O1 3.90500 20 3.90500 0.00000 1.95250 2 Ti1 4.36592 21 -3.90500 0.00000 1.95250 2 Ti1 4.36592 22 0.00000 3.90500 1.95250 2 Ti1 4.36592 23 0.00000 -3.90500 1.95250 2 Ti1 4.36592 24 3.90500 0.00000 -1.95250 2 Ti1 4.36592 25 -3.90500 0.00000 -1.95250 2 Ti1 4.36592 26 0.00000 3.90500 -1.95250 2 Ti1 4.36592 27 0.00000 -3.90500 -1.95250 2 Ti1 4.36592 28 3.90500 1.95250 1.95250 3 O1 4.78263 29 -3.90500 1.95250 1.95250 3 O1 4.78263 30 1.95250 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3 O1 7.30559 126 3.90500 -1.95250 5.85750 3 O1 7.30559 127 -3.90500 -1.95250 5.85750 3 O1 7.30559 128 1.95250 -3.90500 5.85750 3 O1 7.30559 129 -1.95250 -3.90500 5.85750 3 O1 7.30559 130 5.85750 3.90500 -1.95250 3 O1 7.30559 131 -5.85750 3.90500 -1.95250 3 O1 7.30559 132 3.90500 5.85750 -1.95250 3 O1 7.30559 133 -3.90500 5.85750 -1.95250 3 O1 7.30559 134 5.85750 -3.90500 -1.95250 3 O1 7.30559 135 -5.85750 -3.90500 -1.95250 3 O1 7.30559 136 3.90500 -5.85750 -1.95250 3 O1 7.30559 137 -3.90500 -5.85750 -1.95250 3 O1 7.30559 138 3.90500 1.95250 -5.85750 3 O1 7.30559 139 -3.90500 1.95250 -5.85750 3 O1 7.30559 140 1.95250 3.90500 -5.85750 3 O1 7.30559 141 -1.95250 3.90500 -5.85750 3 O1 7.30559 142 3.90500 -1.95250 -5.85750 3 O1 7.30559 143 -3.90500 -1.95250 -5.85750 3 O1 7.30559 144 1.95250 -3.90500 -5.85750 3 O1 7.30559 145 -1.95250 -3.90500 -5.85750 3 O1 7.30559 146 5.85750 1.95250 3.90500 1 Sr1 7.30559 147 -5.85750 1.95250 3.90500 1 Sr1 7.30559 148 1.95250 5.85750 3.90500 1 Sr1 7.30559 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219 -1.95250 -1.95250 -7.81000 1 Sr1 8.28376 220 7.81000 3.90500 0.00000 3 O1 8.73185 221 -7.81000 3.90500 0.00000 3 O1 8.73185 222 3.90500 7.81000 0.00000 3 O1 8.73185 223 -3.90500 7.81000 0.00000 3 O1 8.73185 224 7.81000 -3.90500 0.00000 3 O1 8.73185 225 -7.81000 -3.90500 0.00000 3 O1 8.73185 226 3.90500 -7.81000 0.00000 3 O1 8.73185 227 -3.90500 -7.81000 0.00000 3 O1 8.73185 228 7.81000 0.00000 3.90500 3 O1 8.73185 229 -7.81000 0.00000 3.90500 3 O1 8.73185 230 0.00000 7.81000 3.90500 3 O1 8.73185 231 0.00000 -7.81000 3.90500 3 O1 8.73185 232 3.90500 0.00000 7.81000 3 O1 8.73185 233 -3.90500 0.00000 7.81000 3 O1 8.73185 234 0.00000 3.90500 7.81000 3 O1 8.73185 235 0.00000 -3.90500 7.81000 3 O1 8.73185 236 7.81000 0.00000 -3.90500 3 O1 8.73185 237 -7.81000 0.00000 -3.90500 3 O1 8.73185 238 0.00000 7.81000 -3.90500 3 O1 8.73185 239 0.00000 -7.81000 -3.90500 3 O1 8.73185 240 3.90500 0.00000 -7.81000 3 O1 8.73185 241 -3.90500 0.00000 -7.81000 3 O1 8.73185 242 0.00000 3.90500 -7.81000 3 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