[Ifeffit] ifeffit and feff

[Bruce Ravel]

Ahmed,

I trust you do not mind that I answer your question on the ifeffit
mailing list.  It seems of sufficiently broad interest that an answer
in that forum is appropriate.

You asked:

 AS> I received a note with the latest version of your software. In my
 AS> understanding that the latest version includes the Feff6L without
 AS> a license fee. Does this mean that by downloading the latest
 AS> version of ifeffit, so that I do not need to buy a license of
 AS> feff?

Well, my answer is ether a qualified yes or a qualified no, depending
on what your interests are ;-)

*IF* you are interested only in the extended EXAFS features of Feff
and *IF* you do not think that you need any of the more recent
developments of Feff (most notably, self consistent potentials), then
you probably do not need a license for Feff.  Feff6L is free in both
senses of the word -- it doesn't cost you any money and you may freely
use, modify, and redistribute the code under the terms of its license.
See this post from John Rehr to the mailing list about the Feff6L
license:
  http://millenia.cars.aps.anl.gov/pipermail/ifeffit/2002-November/000169.html


However, if you are interested in computing XANES, partial electronic
densities of state, charge transfer or ab initio Fermi energies, you
will need to license a copy of the latest version of Feff.  If you are
interested in the latest developments of such theoretical topics as
self-consistent potentials, improved self-energies, S02 calculations,
resonant scattering corrections, or a whole host of other features
available in the latest Feff and not available in Feff6L, you will
need to license a copy of the latest version of Feff.


Feff6L is useful code for the extended exafs practitioner.  If that
were not true than Matt would not have been so effusive in his post
yesterday announcing Ifeffit 1.0075.  While Feff6L is useful and
usable for exafs analysis, you must be aware that it is largely
limitted to exafs analysis.  If you need XANES calculations, you need
a Feff8 license.

All clear?
B



-- 
 Bruce Ravel  ----------------------------------- ravel at phys.washington.edu
 Code 6134, Building 3, Room 222
 Naval Research Laboratory                          phone: (1) 202 767 5947
 Washington DC 20375, USA                             fax: (1) 202 767 1697

 NRL Synchrotron Radiation Consortium (NRL-SRC)
 Beamlines X11a, X11b, X23b, X24c, U4b
 National Synchrotron Light Source
 Brookhaven National Laboratory, Upton, NY 11973

 My homepage:    http://feff.phys.washington.edu/~ravel 
 EXAFS software: http://feff.phys.washington.edu/~ravel/software/exafs/