In this reference authors uses a feff7 Can I use feff6 or I need a feef recent version ?

Current versions of Ifeffit ship with a version of Feff6 integrated into the package. Ifeffit, thus Artemis and SixPack also, can use any version of Feff to provide theory for EXAFS analysis. In my experience, Feff6 is usually just fine for EXAFS analysis. You will, of course, need Feff8 to do XANES calculations and other inner shell spectroscopy simulations.

There is a manual that explain how to write a feffit.inp file?

There is. How did we ever find anything before Google? You might consider using either Artemis or SixPack. Most people just starting out find that it is easier to get started using one of the graphical interfaces. That said, you can find the feffit program documentation on Matt's web site and some of my older educational materials were written prior to Artemis. This page helps: http://xafs.org/Tutorials

How I can include the polarization dependence on my calculation?

How polarization works in Feff is unchanged since Feff6. This is from the feff8 document, but it applies just as well to feff6 and feff7: http://leonardo.phys.washington.edu/feff/wiki/index.php?title=POLARIZATION http://leonardo.phys.washington.edu/feff/wiki/index.php?title=ELLIPTICITY 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/