Hi Dr. Matsuura, I am answering CCing this email to the Ifeffit Mailing List http://cars9.uchicago.edu/mailman/listinfo/ifeffit/ which is the most appropriate forum for asking questions about the software. If you have not yet joined the mailing list, we encourage you to do so. I have also taken the liberty of converting the image file you attached into a format that everyone will be able to view. On Tuesday 30 June 2009 02:49:51 am you wrote:
Dear Bruce Ravel
I'm a beginner of IFEFFIT. I'm pleased if you could ask following questions about plotting in Artemis.
1) In a plotted figure as attached, annotation shows "2/path #". What does it mean letter" 2".
Presumably, you have more than one Feff calculation in your Artemis project, one of which still has its default name of "Feff2". To save horizontal space in the legend of the plot, I have Artemis drop the ltters "Feff". So, that legend entry means "Path N from Feff calculation 2".
2) In the plotted figure attached, the sum of each path constituent is not equal to fitting data. The reason of why.
In Ifeffit, we use a complex Fourier transform to convert chi(k) to chi(R), thus chi(R) is a complex function. When the fit is evaluated, the real part of the theoretical chi(R) is compared to the real part of the data chi(R) and the imaginary part is compared to the imaginary part. You have plotted the magnitude of this complex function. You should not expect the sum of the moduli of the paths to equal the modulus of the sum of the paths. For a complex function, summation and mudulus are not commutative operations. B
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Metallic Glass Inorganic Materials Joinning Technology Development
Institute for Materials Research, Tohoku University,Sendai, 980-8577,Japan
Dr. Makoto Matsuura
e-mail:m_matsuura@imr.tohoku.ac.jp
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-- Bruce Ravel ------------------------------------ bravel@bnl.gov National Institute of Standards and Technology Synchrotron Methods Group at NSLS --- Beamlines U7A, X24A, X23A2 Building 535A Upton NY, 11973 My homepage: http://xafs.org/BruceRavel EXAFS software: http://cars9.uchicago.edu/~ravel/software/exafs/
