On Wednesday 29 October 2003 04:55 pm, k-kupiecki@northwestern.edu wrote:
Hi,
I'm also a novice with the Athena/Artemis Ifeffit software.
I've read through the online documentation for both and I'm now trying to go through the Cu example in Chapter 2 of the Artemis manual.
Can someone please tell me where I input the following information into Artemis (I've tried in the fields on the Path parameter screen, but it gives me an error when I go to fit)? (from page 19 of the manual):
We will then define extremely simple math exressions for the corresponding path parameters of the first shell.
s02 0:1 amp e0 0:1 e0 delr 0:1 delr sigma2 0:1 ss
Kristine, Hmmm.... this is a little embarassing. I have to apologize for the state of the Artemis document. It suffers rather alot right now from bad stream-of-consciousness writing. My goal in the chapter on the copper fit was to walk through the steps of an increasingly complicated fit. Start with single shell, then two shells, then three. Then do four shells + all the necessary multiple scattering. Then introduce the concept of multiple-data-set fitting. As I was writing it a few months ago, I didn't want to interupt my (ever-so-brilliant) train of thought to make a bunch of screenshots demonstrating what I was talking about, so I tried to develop a text-only shorthand to explain what I meant. The "0:1" was my shorthand for indicating that this was path number 1 (i.e. the first one) from data set number 0 (also intended to be the first one). Obviously confusing. Sigh. In an attempt to clarify the situation, I made four screenshots from the single shell project file that gets distributed with the program. Point your browser at this directory: http://feff.phys.washington.edu/~ravel/misc/ You will find the four screenshots I just made: artemis_cu1.png the view of the data artemis_cu2.png the view of the guess and set parameters artemis_cu3.png the view of the description of the feff calculation artemis_cu4.png the view of the first path I think this should make it clear what goes where. Note that these shots were taken of Artemis getting ready to fit just the fist shell of the copper data. Thus paths contained in feff0002.dat through feff0005.dat are not included in the fit. The ones not included in the fit are written in brown text in the list on the right side of the window. In subsequent fits, when those included in the fit, you can edit their parameters by clicking on them. That will display something that looks very much like the artemis_cu4.png image, but with the information relevant to that path. Taking language from those images on my web site, the bit in the document that you are asking about would have been much better written as: FEFF0: feff0001.dat s02 = amp e0 = e0 delr = delr sigma2 = ss That would have, perhaps, been clearer. Certainly more consistent with the appearence of the program. And still more concise than an entire screenshot at that point in the doc. Hope that helps, sorry for the confusion, and don't hesitate to keep asking questions on the mailing list. And, contrary to the sentiment in your subject line, there are no silly questions, just silly programmers. B -- Bruce Ravel ----------------------------------- ravel@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 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/