- Ifeffit - millenia.cars.aps.anl.gov

Re: [Ifeffit] Ifeffit Digest, Vol 52, Issue 9
by Michel Jaouen 18 Jun '07

18 Jun '07

Dear lena, >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 >(9.5?) clusters. Attached is my *.inp file for the 9.5? cluster and a >summary of the XANES for increasing cluster sizes from 6.5? to 9.5?. You >can see that there are still significant changes as the cluster size is >increased from 8.5 to 9.5?. In particular, I find a double peak feature >in the first 5eV after the edge onset, which is not observed >experimentally. It is a normal behavior: when increasing the cluster's size, you are adding more MS paths and then it appears coresponding peaks. It is a general trend for xanes:the measured signal is a probe up to a given distance for MS, a distance you didn't know a priori. Thus the game is to start from a rather small cluster, compute the xanes, compare to the experiment. If some features are missing, increase the size and so on till you obtain (if lucky) all experimental fine structures. On the opposite, as soon as it appears fine structures which don't exist in the experiment reduce the size. > 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? I have been working a lot on STO and have many exchange about this material with John Rehr. In fact you can obtain a quite good match with the experiment (peaks' positions) if you reduce the lattice parameter by 5% (RMULTIPLIER=0.95, see the attached figure). Of course such a reduction is unphysical but from John's own words :"Also regarding SrTiO3, I'm now thinking that the self-energy might be responsible for the need to use an RMULT 0.95." So either you the Rmultiplier trick or you try the feff8.5 version that includes some improvements to the self-energy (using low-loss and the sum rules for normalization). In any case, feff has to much intensity at the edge onset (sigma*) for light elements like Oxygen. Two other comments: why adding a real part vr=1.4eV? I don't find this necessary here from my numerous calculations (it is responsible for the hump at the bottom of the pi* which doesn't exist in the experiment: a positive vr induces a red-shift for the spectrum, look at the ldos). I suggest also not to use the default for lmax (-1), but instead lmax=2 for all atoms (spd basis). You can also try to go up to lmax=3 (spdf basis) because Sr is quite heavy and it can help in some case (for pure Ni for instance, to reproduce the K edge, you must go up to f states). I hope it can help you. Best regards, Michel -- __________________________________________ Michel Jaouen Universite de Poitiers - UFR Sciences - SP2MI LMP UMR 6630-CNRS Boulevard Pierre et Marie Curie - Teleport 2 BP 30179 86962 Futuroscope - Chasseneuil Cedex France Tel : (33) 5 49 49 67 37 Fax : (33) 5 49 49 66 92 e-mail : Michel.Jaouen(a)univ-poitiers.fr __________________________________________

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Re: [Ifeffit] convergence of XANES for STO
by Feng Wang 18 Jun '07

18 Jun '07

Hi Lena, It is no suprising to see the change of the fine structure near the edge within a cluster of that size, because of the long mean free path of the photoelectron. You used a broadening of 0.2eV in your FEFF input, which should give you more details than your experiments. Good luck, Feng > 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(a)cornell.edu > --------------------------------- ==================================== EM group, NINT 11421 Saskatachewan Drive Edmonton, Canada T6G 2M9

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convergence of XANES for STO
by Lena Fitting 18 Jun '07

18 Jun '07

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(a)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 3.90500 1.95250 3 O1 4.78263 31 -1.95250 3.90500 1.95250 3 O1 4.78263 32 3.90500 -1.95250 1.95250 3 O1 4.78263 33 -3.90500 -1.95250 1.95250 3 O1 4.78263 34 1.95250 -3.90500 1.95250 3 O1 4.78263 35 -1.95250 -3.90500 1.95250 3 O1 4.78263 36 3.90500 1.95250 -1.95250 3 O1 4.78263 37 -3.90500 1.95250 -1.95250 3 O1 4.78263 38 1.95250 3.90500 -1.95250 3 O1 4.78263 39 -1.95250 3.90500 -1.95250 3 O1 4.78263 40 3.90500 -1.95250 -1.95250 3 O1 4.78263 41 -3.90500 -1.95250 -1.95250 3 O1 4.78263 42 1.95250 -3.90500 -1.95250 3 O1 4.78263 43 -1.95250 -3.90500 -1.95250 3 O1 4.78263 44 1.95250 1.95250 3.90500 1 Sr1 4.78263 45 -1.95250 1.95250 3.90500 1 Sr1 4.78263 46 1.95250 -1.95250 3.90500 1 Sr1 4.78263 47 -1.95250 -1.95250 3.90500 1 Sr1 4.78263 48 1.95250 1.95250 -3.90500 1 Sr1 4.78263 49 -1.95250 1.95250 -3.90500 1 Sr1 4.78263 50 1.95250 -1.95250 -3.90500 1 Sr1 4.78263 51 -1.95250 -1.95250 -3.90500 1 Sr1 4.78263 52 3.90500 3.90500 0.00000 3 O1 5.52250 53 -3.90500 3.90500 0.00000 3 O1 5.52250 54 3.90500 -3.90500 0.00000 3 O1 5.52250 55 -3.90500 -3.90500 0.00000 3 O1 5.52250 56 3.90500 0.00000 3.90500 3 O1 5.52250 57 -3.90500 0.00000 3.90500 3 O1 5.52250 58 0.00000 3.90500 3.90500 3 O1 5.52250 59 0.00000 -3.90500 3.90500 3 O1 5.52250 60 3.90500 0.00000 -3.90500 3 O1 5.52250 61 -3.90500 0.00000 -3.90500 3 O1 5.52250 62 0.00000 3.90500 -3.90500 3 O1 5.52250 63 0.00000 -3.90500 -3.90500 3 O1 5.52250 64 3.90500 3.90500 1.95250 2 Ti1 5.85750 65 -3.90500 3.90500 1.95250 2 Ti1 5.85750 66 3.90500 -3.90500 1.95250 2 Ti1 5.85750 67 -3.90500 -3.90500 1.95250 2 Ti1 5.85750 68 0.00000 0.00000 5.85750 2 Ti1 5.85750 69 3.90500 3.90500 -1.95250 2 Ti1 5.85750 70 -3.90500 3.90500 -1.95250 2 Ti1 5.85750 71 3.90500 -3.90500 -1.95250 2 Ti1 5.85750 72 -3.90500 -3.90500 -1.95250 2 Ti1 5.85750 73 0.00000 0.00000 -5.85750 2 Ti1 5.85750 74 5.85750 0.00000 1.95250 3 O1 6.17435 75 -5.85750 0.00000 1.95250 3 O1 6.17435 76 0.00000 5.85750 1.95250 3 O1 6.17435 77 0.00000 -5.85750 1.95250 3 O1 6.17435 78 1.95250 0.00000 5.85750 3 O1 6.17435 79 -1.95250 0.00000 5.85750 3 O1 6.17435 80 0.00000 1.95250 5.85750 3 O1 6.17435 81 0.00000 -1.95250 5.85750 3 O1 6.17435 82 5.85750 0.00000 -1.95250 3 O1 6.17435 83 -5.85750 0.00000 -1.95250 3 O1 6.17435 84 0.00000 5.85750 -1.95250 3 O1 6.17435 85 0.00000 -5.85750 -1.95250 3 O1 6.17435 86 1.95250 0.00000 -5.85750 3 O1 6.17435 87 -1.95250 0.00000 -5.85750 3 O1 6.17435 88 0.00000 1.95250 -5.85750 3 O1 6.17435 89 0.00000 -1.95250 -5.85750 3 O1 6.17435 90 5.85750 1.95250 0.00000 1 Sr1 6.17435 91 -5.85750 1.95250 0.00000 1 Sr1 6.17435 92 1.95250 5.85750 0.00000 1 Sr1 6.17435 93 -1.95250 5.85750 0.00000 1 Sr1 6.17435 94 5.85750 -1.95250 0.00000 1 Sr1 6.17435 95 -5.85750 -1.95250 0.00000 1 Sr1 6.17435 96 1.95250 -5.85750 0.00000 1 Sr1 6.17435 97 -1.95250 -5.85750 0.00000 1 Sr1 6.17435 98 3.90500 3.90500 3.90500 3 O1 6.76366 99 -3.90500 3.90500 3.90500 3 O1 6.76366 100 3.90500 -3.90500 3.90500 3 O1 6.76366 101 -3.90500 -3.90500 3.90500 3 O1 6.76366 102 3.90500 3.90500 -3.90500 3 O1 6.76366 103 -3.90500 3.90500 -3.90500 3 O1 6.76366 104 3.90500 -3.90500 -3.90500 3 O1 6.76366 105 -3.90500 -3.90500 -3.90500 3 O1 6.76366 106 3.90500 0.00000 5.85750 2 Ti1 7.03984 107 -3.90500 0.00000 5.85750 2 Ti1 7.03984 108 0.00000 3.90500 5.85750 2 Ti1 7.03984 109 0.00000 -3.90500 5.85750 2 Ti1 7.03984 110 3.90500 0.00000 -5.85750 2 Ti1 7.03984 111 -3.90500 0.00000 -5.85750 2 Ti1 7.03984 112 0.00000 3.90500 -5.85750 2 Ti1 7.03984 113 0.00000 -3.90500 -5.85750 2 Ti1 7.03984 114 5.85750 3.90500 1.95250 3 O1 7.30559 115 -5.85750 3.90500 1.95250 3 O1 7.30559 116 3.90500 5.85750 1.95250 3 O1 7.30559 117 -3.90500 5.85750 1.95250 3 O1 7.30559 118 5.85750 -3.90500 1.95250 3 O1 7.30559 119 -5.85750 -3.90500 1.95250 3 O1 7.30559 120 3.90500 -5.85750 1.95250 3 O1 7.30559 121 -3.90500 -5.85750 1.95250 3 O1 7.30559 122 3.90500 1.95250 5.85750 3 O1 7.30559 123 -3.90500 1.95250 5.85750 3 O1 7.30559 124 1.95250 3.90500 5.85750 3 O1 7.30559 125 -1.95250 3.90500 5.85750 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 149 -1.95250 5.85750 3.90500 1 Sr1 7.30559 150 5.85750 -1.95250 3.90500 1 Sr1 7.30559 151 -5.85750 -1.95250 3.90500 1 Sr1 7.30559 152 1.95250 -5.85750 3.90500 1 Sr1 7.30559 153 -1.95250 -5.85750 3.90500 1 Sr1 7.30559 154 5.85750 1.95250 -3.90500 1 Sr1 7.30559 155 -5.85750 1.95250 -3.90500 1 Sr1 7.30559 156 1.95250 5.85750 -3.90500 1 Sr1 7.30559 157 -1.95250 5.85750 -3.90500 1 Sr1 7.30559 158 5.85750 -1.95250 -3.90500 1 Sr1 7.30559 159 -5.85750 -1.95250 -3.90500 1 Sr1 7.30559 160 1.95250 -5.85750 -3.90500 1 Sr1 7.30559 161 -1.95250 -5.85750 -3.90500 1 Sr1 7.30559 162 7.81000 0.00000 0.00000 3 O1 7.81000 163 -7.81000 0.00000 0.00000 3 O1 7.81000 164 0.00000 7.81000 0.00000 3 O1 7.81000 165 0.00000 -7.81000 0.00000 3 O1 7.81000 166 0.00000 0.00000 7.81000 3 O1 7.81000 167 0.00000 0.00000 -7.81000 3 O1 7.81000 168 7.81000 0.00000 1.95250 2 Ti1 8.05036 169 -7.81000 0.00000 1.95250 2 Ti1 8.05036 170 0.00000 7.81000 1.95250 2 Ti1 8.05036 171 0.00000 -7.81000 1.95250 2 Ti1 8.05036 172 3.90500 3.90500 5.85750 2 Ti1 8.05036 173 -3.90500 3.90500 5.85750 2 Ti1 8.05036 174 3.90500 -3.90500 5.85750 2 Ti1 8.05036 175 -3.90500 -3.90500 5.85750 2 Ti1 8.05036 176 7.81000 0.00000 -1.95250 2 Ti1 8.05036 177 -7.81000 0.00000 -1.95250 2 Ti1 8.05036 178 0.00000 7.81000 -1.95250 2 Ti1 8.05036 179 0.00000 -7.81000 -1.95250 2 Ti1 8.05036 180 3.90500 3.90500 -5.85750 2 Ti1 8.05036 181 -3.90500 3.90500 -5.85750 2 Ti1 8.05036 182 3.90500 -3.90500 -5.85750 2 Ti1 8.05036 183 -3.90500 -3.90500 -5.85750 2 Ti1 8.05036 184 7.81000 1.95250 1.95250 3 O1 8.28376 185 -7.81000 1.95250 1.95250 3 O1 8.28376 186 1.95250 7.81000 1.95250 3 O1 8.28376 187 -1.95250 7.81000 1.95250 3 O1 8.28376 188 7.81000 -1.95250 1.95250 3 O1 8.28376 189 -7.81000 -1.95250 1.95250 3 O1 8.28376 190 1.95250 -7.81000 1.95250 3 O1 8.28376 191 -1.95250 -7.81000 1.95250 3 O1 8.28376 192 5.85750 0.00000 5.85750 3 O1 8.28376 193 -5.85750 0.00000 5.85750 3 O1 8.28376 194 0.00000 5.85750 5.85750 3 O1 8.28376 195 0.00000 -5.85750 5.85750 3 O1 8.28376 196 7.81000 1.95250 -1.95250 3 O1 8.28376 197 -7.81000 1.95250 -1.95250 3 O1 8.28376 198 1.95250 7.81000 -1.95250 3 O1 8.28376 199 -1.95250 7.81000 -1.95250 3 O1 8.28376 200 7.81000 -1.95250 -1.95250 3 O1 8.28376 201 -7.81000 -1.95250 -1.95250 3 O1 8.28376 202 1.95250 -7.81000 -1.95250 3 O1 8.28376 203 -1.95250 -7.81000 -1.95250 3 O1 8.28376 204 5.85750 0.00000 -5.85750 3 O1 8.28376 205 -5.85750 0.00000 -5.85750 3 O1 8.28376 206 0.00000 5.85750 -5.85750 3 O1 8.28376 207 0.00000 -5.85750 -5.85750 3 O1 8.28376 208 5.85750 5.85750 0.00000 1 Sr1 8.28376 209 -5.85750 5.85750 0.00000 1 Sr1 8.28376 210 5.85750 -5.85750 0.00000 1 Sr1 8.28376 211 -5.85750 -5.85750 0.00000 1 Sr1 8.28376 212 1.95250 1.95250 7.81000 1 Sr1 8.28376 213 -1.95250 1.95250 7.81000 1 Sr1 8.28376 214 1.95250 -1.95250 7.81000 1 Sr1 8.28376 215 -1.95250 -1.95250 7.81000 1 Sr1 8.28376 216 1.95250 1.95250 -7.81000 1 Sr1 8.28376 217 -1.95250 1.95250 -7.81000 1 Sr1 8.28376 218 1.95250 -1.95250 -7.81000 1 Sr1 8.28376 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 O1 8.73185 243 0.00000 -3.90500 -7.81000 3 O1 8.73185 244 7.81000 3.90500 1.95250 2 Ti1 8.94748 245 -7.81000 3.90500 1.95250 2 Ti1 8.94748 246 3.90500 7.81000 1.95250 2 Ti1 8.94748 247 -3.90500 7.81000 1.95250 2 Ti1 8.94748 248 7.81000 -3.90500 1.95250 2 Ti1 8.94748 249 -7.81000 -3.90500 1.95250 2 Ti1 8.94748 250 3.90500 -7.81000 1.95250 2 Ti1 8.94748 251 -3.90500 -7.81000 1.95250 2 Ti1 8.94748 252 7.81000 3.90500 -1.95250 2 Ti1 8.94748 253 -7.81000 3.90500 -1.95250 2 Ti1 8.94748 254 3.90500 7.81000 -1.95250 2 Ti1 8.94748 255 -3.90500 7.81000 -1.95250 2 Ti1 8.94748 256 7.81000 -3.90500 -1.95250 2 Ti1 8.94748 257 -7.81000 -3.90500 -1.95250 2 Ti1 8.94748 258 3.90500 -7.81000 -1.95250 2 Ti1 8.94748 259 -3.90500 -7.81000 -1.95250 2 Ti1 8.94748 260 5.85750 3.90500 5.85750 3 O1 9.15804 261 -5.85750 3.90500 5.85750 3 O1 9.15804 262 3.90500 5.85750 5.85750 3 O1 9.15804 263 -3.90500 5.85750 5.85750 3 O1 9.15804 264 5.85750 -3.90500 5.85750 3 O1 9.15804 265 -5.85750 -3.90500 5.85750 3 O1 9.15804 266 3.90500 -5.85750 5.85750 3 O1 9.15804 267 -3.90500 -5.85750 5.85750 3 O1 9.15804 268 5.85750 3.90500 -5.85750 3 O1 9.15804 269 -5.85750 3.90500 -5.85750 3 O1 9.15804 270 3.90500 5.85750 -5.85750 3 O1 9.15804 271 -3.90500 5.85750 -5.85750 3 O1 9.15804 272 5.85750 -3.90500 -5.85750 3 O1 9.15804 273 -5.85750 -3.90500 -5.85750 3 O1 9.15804 274 3.90500 -5.85750 -5.85750 3 O1 9.15804 275 -3.90500 -5.85750 -5.85750 3 O1 9.15804 276 5.85750 5.85750 3.90500 1 Sr1 9.15804 277 -5.85750 5.85750 3.90500 1 Sr1 9.15804 278 5.85750 -5.85750 3.90500 1 Sr1 9.15804 279 -5.85750 -5.85750 3.90500 1 Sr1 9.15804 280 5.85750 5.85750 -3.90500 1 Sr1 9.15804 281 -5.85750 5.85750 -3.90500 1 Sr1 9.15804 282 5.85750 -5.85750 -3.90500 1 Sr1 9.15804 283 -5.85750 -5.85750 -3.90500 1 Sr1 9.15804 284 END

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Trouble of Path & Data List data of Artemis
by Joji Kuniya 15 Jun '07

15 Jun '07

Dear Bruce I tried fitting to my EXAFS date by Artemis program. Abruptly fitted and Path spectrum was broaden. So, I checked the paths in the Data & Path list and the feff calculated results. So that, the paths data in the Data & Path is differed from the left side feff calculated data(of course, number of # of the interpretation and the path of data & Path is the same). This troube is almostly? dissoleved when new Artemis was opened. But, scarcely this troubel have occured again. I reinstalled your feffit program, but I have been occasionally encountering. Did yo have some experience like this? Please teach me what to do to clear thus trouble. Thank you Joji Kuniya

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XANES / NEXAFS with feff8.4
by s440697＠stud.uni-goettingen.de 15 Jun '07

15 Jun '07

Hallo @all, (first at all, sorry for my bad english) i'm a student working on my diploma thesis (nexafs/xanes) and my job is to simulate with FEFF 8.4 spectra, for example absorption as a function of energy (mu_(E)). I'm a newbie in this topic and i tried to get the k-edge of Sulfur for the substance gypsum (CaSO4 * 2(H2O)) and pyrite (FeS2). I'm interested in the XANES-range of the spectra not the EXAFS. I get everytime my peaks at ~2472 eV for Sulfur as absorber whatever substance i use (gypsum, pyrite,...). There are no differences with the peak position on the energy-scale or shifts. I'm really confused :-( I think, there should be differences in the spectra... I send you two feff.inp files from my feff-runs. My source is the mineralogy database (http://rruff.geo.arizona.edu/AMS/amcsd.php) where i get the data for the unitcell. Then i put the data in the XtalDraw program to get the positions of the Atoms in Angstrom, by the way i get i nice 3D-View of the unitcell :-). Then i put the values of the positions into feff... I simulated pyrite with 12 atoms and gypsum with 48. I'm appreciative for every help :-) ciao, Eckhard --------------------------------- Eckhard Bosman e.bosman(a)stud.uni-goettingen.de +49 (0)551-39-14441 Raum: E0.104 Institut für Röntgenphysik Friedrich-Hund-Platz 1 37077 Göttingen Germany

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How to make a hole on feff.inp file
by Joji Kuniya 07 Jun '07

07 Jun '07

Dear members I have been treating with an EXAFS spectra of an oxide crystals. This crystal has some holes (defects) in the system.I have not a good idea in handling of the hole system, I put hydrogen instead of the hole. I think this procedure is not appropriated. Please teach me how to make hole on a feff.inp file. Thank you. Joji Kuniya

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bond distance resolution and correlation of parameters in MS analyses?
by MarkBondin 06 Jun '07

06 Jun '07

Hi, I would like general opinions of some EXAFS practioners in regards to the most widely accepted methods for bond distance resolution and correlation of parameters in both single scattering (SS) and multiple scattering (MS) EXAFS refinements and if these can be said to differ? 1)Does the equation for bond distance resolution (r = pi/2deltak) only apply to SS? I have held the opinion that this can be applied to MS analysis however I have recently been informed that this equation does not correctly describe distance resolution in MS analyses. The paper in Coord. Chem. Rev. 2005, 249, 141-160 describes this and is this concordant with the views of the wider EXAFS community? 2) What is the actual equation which defines the determinacy of a fitting procedure and does this differ between SS and MS analyses? For MS analyses there has been a recently published equation (Coord. Chem. Rev. 2005, 249, 141-160) which takes into acount the number of dimensions used in the analyses and is this only relevant to MS analyses of data? This has also been expressed in the paper by Binsted (Biochemistry. 1992, 31, 12117-12125) however a different equation has been detailed by Stern (Phys. Rev. B. 1993, 48, 9825-9827) which I have been using as a guide in my MS analyses. Is this acceptable? Any thoughts and opinions would be greatly appreciated as this relates directly to corrections suggested to be made to my PhD thesis! Many thanks, Mark

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help with CoCr bimetallic catalyst
by codruta.zoican＠yale.edu 06 Jun '07

06 Jun '07

I have been, working with a bimetallic Co/Cr catalyst supported on a silica template for synthesis of single wall carbon nanotubes. Recently I have performed some analysis at the NSLS. It is clear from the spectra in R space that the interatomic distances are modified compared to the monometallic catalyst therefore I am dealing with an alloy. Does anyone have or know about a model that would allow me to get a coordination nomber using Artemis. Thank you, Codruta.

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Re: [Ifeffit] Deconvolution of XANES spectra
by Gerald Seidler 03 Jun '07

03 Jun '07

Dear Jakob, Attached you will find my student's recent paper on deconvolution of XANES and EXAFS using iterative maximum-likelihood algorithms (TT Fister et al, Phys Rev B vol75, artNo.174106 ). Our software is available through EPAPS, but it is in Mathematica, which I realize isn't most convenient for many users. We will have matlab/scilab versions ready by the end of the summer which will include both the Richardson-Lucy (ratio) method from our paper and also the deCittert (linear) method previously used with good success by Babanov. The matlab/scilab package will come with a GUI so that it should be easy to use, even for experimenters with no knowledge of those programming environments. After that, we'll start working on making a stand-alone executable... but note that scilab is free (it is the shareware copy of matlab). Let me know if you'd like to talk about your particular application. We have a pretty good idea about the likely performance of our approach for different spectra, and I would be happy to run some test deconvolutions for you. Cheers, Jerry ------------------------- Gerald T. Seidler Associate Professor, Physics University of Washington ---------- Forwarded message ---------- Date: Sun, 3 Jun 2007 13:55:42 +0200 From: Frommer Jakob <jakob.frommer(a)env.ethz.ch> Reply-To: XAFS Analysis using Ifeffit <ifeffit(a)millenia.cars.aps.anl.gov> To: ifeffit(a)millenia.cars.aps.anl.gov Subject: [Ifeffit] Deconvolution of XANES spectra Dear all, I would like to know whether some of you do have experience in deconvoluting XANES spectra in order to remove both, lifetime and experimental broadening. If so, what programs are you using for this purpose? Any hint would be of great help With many thanks and best wishes Jakob

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Deconvolution of XANES spectra
by Frommer Jakob 03 Jun '07

03 Jun '07

Dear all, I would like to know whether some of you do have experience in deconvoluting XANES spectra in order to remove both, lifetime and experimental broadening. If so, what programs are you using for this purpose? Any hint would be of great help With many thanks and best wishes Jakob ___________________________________________________ Jakob Frommer Soil Chemistry Group Institute of Biogeochemistry and Pollutant Dynamics, ETH Zürich Universitätstrasse 16, CHN F19 CH - 8092 Zürich Tel: +41 44 632 87 58 Fax: +41 44 633 11 18 Email: jakob.frommer(a)env.ethz.ch http://www.ito.ethz.ch/SoilChem/

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