On Friday, April 01, 2011 05:03:17 pm Ping, Yuan wrote:
Dear IFEFFIT experts:
Is it possible to add a k^3 term in the phase for fitting to take into account anharmonic effect? The fitted coefficient will be proportional to the 3rd cumulant of Debye-Waller factor. I work with high-temperature high-pressure systems where anharmonic effect is not negligible.
Thanks. Yuan Ping
Hi Yuan, Here is the relevant page from the Ifeffit reference manual: http://cars9.uchicago.edu/~ifeffit/refman/node51.html You want to use the "3rd" path parameter, which adds a term proportional to C3*k^3 to the sine function in the exafs equation. See the attached figure for the place in Artemis where this parameter is introduced. HTH, B -- 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/
