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RE: strange distance obtained using atoms



The reason is that you have Ti and Zr both present in your input file at the B site in ABO3 formula but in the unit cell ABO3 there must be just one type of atoms, Ti or Zr, at any given B site. So, if you want to model Ti edge, use your input file for Pb,Ti and O only, where Ti is the central atom. If you are using it for Zr K-edge, omit Ti from the list. If it is random solution of PbTiO3(x)-PbZrTiO3(1-x) you will have to include both Ti-Ti, Ti-Zr for Ti edge and Zr-Zr and Zr-Ti for Zr edge EXAFS analyses. To model FEFF for mixed bonds, modify the feff.inp file that you will have constructed for PbTiO3, by replacing 6 lines corresponding to the  3NN shell of Ti atoms (there should be 6 Ti-Ti bonds) by 6 lines copied from the feff.inp file that corresponds to the  3NN shell of Zr atoms calculated for PbZrO3. Then run feff, and you will obtain feffxxxx.dat files for Ti-Zr bond. Do similar procedure for Zr-Ti FEFF modeling. 
 
Hope it helps,
 
Anatoly
 
Anatoly Frenkel
Associate Professor
Physics Department
Yeshiva University
245 Lexington Avenue
New York, NY 10016
anatoly.frenkel@yu.edu

[Anatoly Frenkel] 
 -----Original Message-----
From: FEFFUSERS-owner@u.washington.edu [mailto:FEFFUSERS-owner@u.washington.edu]On Behalf Of Valmor Mastelaro
Sent: Thursday, November 11, 2004 9:11 AM
To: FEFF Users
Subject: strange distance obtained using atoms

Hello Bruce, how are you??


Bruce, I´m using the atoms program to obtain the feff.inp file for a PZT compound. when I introduced the crystallographic informations on the atoms, I obtained only one distance that is too short to be true, Ti-Zr = 0.483

I verify all the crystallographic parameters in the literature and they seens to be correct. (Journal of Physics: condensed matter 10, 6251-6269 (1998).

I ´m sending the atoms.inp file that I have used.

Can you help me, please?

best regards

Valmor

Valmor Roberto Mastelaro
Instituto de Física de São Carlos
Universidade de São Paulo
C.P. 369
CEP 1360-970
São Carlos, S.P. Brasil
Tel: 5516 3373-9828
Fax: 5516 3373-9824
http://www.ccmc.if.sc.usp.br