- Ifeffit - millenia.cars.aps.anl.gov

new user contributions page
by Bruce Ravel 26 Nov '03

26 Nov '03

Hi folks, A couple weeks ago, Scott sent me a wonderful collection of Artemis project files which serve as a nifty tutorial on how to use Artemis. To quote from Scott's README file: "The tutorial is meant for people who understand the rudiments of EXAFS analysis, but have little practical experience. In other words, I assume you know what a "path" is, but are unsure of how to know what paths to include in a fit." For anyone just starting out using Artemis or anyone who would like some tips and hints from an expert user, Scott's tutorial should prove very helpful, indeed. I have started a page of user contributed materials. Here's the URL: http://leonardo.phys.washington.edu/~ravel/software/exafs/contrib.html Scott's tutorial is there. I'd certainly enjoy having more things to put on that page.... Regards, Bruce -- Bruce Ravel ----------------------------------- ravel(a)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/

4 6

Scott's tutorial
by Tamas Varga 26 Nov '03

26 Nov '03

1 0

vacation time!
by Bruce Ravel 25 Nov '03

25 Nov '03

Hi! This is my last message of the day to the mailing list. I promise! I wanted to let you all know that I will be taking some vacation time starting on Friday. I will not be near computers while I am gone (that's what makes it a vacation ;-) so I will not be responding to any email. Don't stop sending in bug reports and feature suggestions while I am away! I will read them all upon my return in mid-December. Regards, Bruce -- Bruce Ravel ----------------------------------- ravel(a)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/

1 0

phase corrections and saving files
by Bruce Ravel 25 Nov '03

25 Nov '03

Hi folks, I have received a few questions recently on the topic of saving data to column data files after doing a phase corrected Fourier transform. Both Athena and Artemis will do this. Let me explain how it works. ** In Athena, when you save chi(R) as a column data file for the current group it will save the phase corrected chi(R) if the button for central atom phase corrections is checked for that group. ** In Artemis, you can save chi(R) for the data, the fit, or any part of the fit. If a path has been chosen for the phase correction on the data page, then the Fourier transform will be done using that path's phase correction before writing out chi(R). ** Thus the rule for both programs is simple. If you select a phase correction, it will be applied before writing out chi(R). ** For both programs, chi(q) will likewise be written out with the phase correction is the phase correction is chosen. That is, if the phase correction is chosen, it will be applied to the forward transform and the backward transform will be done on that spectrum. ** Neither program writes out a phase corrected chi(k). ** Athena uses a central atom phase correction and no scattering atom correction. Artemis uses both a central and scattering atom phase correction, but only that of the path selected for the correction. The fit in Artemis is *always* done using the non-phase-corrected data and the non-phase-corrected feffNNNN.dat files. ** There was a recent discussion on the mailing list about doing phase *and* amplitude corrections. Neither Athena nor Artemis does that at this time. If you observe a situation where either program does not behave as advertised, let me know so I can fix it for the next release. Regards, B -- Bruce Ravel ----------------------------------- ravel(a)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/

1 0

Fwd: athena - Win 98 and Win NT
by Bruce Ravel 25 Nov '03

25 Nov '03

Brad, I am passing this along to the mailing list to see if anyone else has any better wisdom for you. But I'll take a stab. Win98: did you put "SHELL=C:\COMMAND.COM /E:4096 /P" into `config.sys', as the Win98 instructions on my and Matt's web sites suggest? Otherwise I am not familiar enough with Win98 to provide better guidance. WinNT: I have never seen the message you described and don't quite know what it means. What happens on NT if you install the stuff in to C:\Program Files\ rather than onto the F: disk? Again, I am not very familiar with NT (I've never actually haad it on a machine that I own.) Win2K: Whew! Using this seems like the path of least resistance. Anyone else have any wisdom? B ---------- Forwarded Message ---------- Subject: athena - Win 98 and Win NT Date: Tue, 25 Nov 2003 14:32:31 -0600 (CST) From: Brad Lindseth <bjl(a)ccrc.wustl.edu> To: ravel(a)phys.washington.edu Hi, We took some XAFS data a week ago at the APS. I installed athena to look at the data. Here is my report: 1. installed on Win 98: athena runs, but says "Error: Runtime exception" in the DOS window. And then a Microsoft Visual C++ Runtime library box says: Runtime Error! Program c:\ifeffit\grwnd.exe abnormal program termination. 2. installed on WinNT 4.0: in the DOS window it says: F:\PROGRA~1\Ifeffit>athena Can't load 'C:\TEMP\athena\{62B3D752-A76A-4C15-B621-8205B2665DBC}\/auto/Ifeffit/ Ifeffit.dll' for module Ifeffit: load_file:The paging file is too small for this operation to complete at DynaLoader.pm line 206. BEGIN failed--compilation aborted at athena line 59. 3. windows 2000 installation works just fine. Should I just use the win 2000 installation, or is there a simple fix for the other two? Thanks, Brad Lindseth # Brad Lindseth # Graduate Student # Washington University # Phone: (314) 977-0283 # E-mail: bjl1(a)cec.wustl.edu # Web: http://clarion.cec.wustl.edu/~bjl1/ ------------------------------------------------------- -- Bruce Ravel ----------------------------------- ravel(a)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/

2 1

new release of Athena and Artemis
by Bruce Ravel 25 Nov '03

25 Nov '03

Hi folks, I just posted a new tarball containing the source code for Athena 0.8.024 and Artemis 0.6.009. The Windows updater is not quite ready yet, but as soon as it is, Windows users will be able to update their computer. This is mostly a bug fix release, but I did add a new feature to Athena last week while I was at NSLS. You can now align data using a reference channel. The documentation has not yet been updated to reflect this new feature, but I describe it briefly on the News page for the latest release: http://leonardo.phys.washington.edu/~ravel/software/exafs/NEWS Alignment to a reference channel should work equally well if the reference spectrum is of the same edge as the data or of another element with a nearby edge. Regards, B -- Bruce Ravel ----------------------------------- ravel(a)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/

1 0

Fwd: Line stlye in Artemis
by Bruce Ravel 24 Nov '03

24 Nov '03

> I am using Athena and Artemis to analysis my EXAFS data. I want to > plot the raw data in dashed line and the fitting in solid line. I > tried "settings","plot" selections in Artemis(version 1.2.4), but no > line style choice is available. Can you please tell me how to change > the settings? > -Chuanyong Jing Chuanyong, I am taking the liberty of replying to your email via the Ifeffit mailing list. There is currently no ability to change the linestyle in Artemis. Sorry. It would be resonable to have separate linestyles for the data, the fit, and the other components of the fit (i.e. background and paths). I will put that on the list of things to do. I should point out that I consider the graphics in Artemis and Athena (that is the pgplot graphics that are provided via ifeffit) to be for quick-n-dirty, on screen plotting. I don't make any great effort to provide graphics that are beautiful enough for publication. For that, I think it is better to export the components of the desired plot to column data files and use a program (Origin, Kaleidagraph, Igor, XMGrace, SciGraphica, or whatever) that is intended for making beautiful, publication-quality plots. The level of graphical sophistication that one expects for publication is beyond the scope of what Artemis and Athena are intended to do. Still, your request for different line types is a reasonable one and I will implement it eventually. Ragards, B -- Bruce Ravel ----------------------------------- ravel(a)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/

1 0

Some direction
by H H 23 Nov '03

23 Nov '03

Since, I am new in doing XAFS fitting, I hope some one just direct me little bit. In order to my fitting, I always filter each individual shell and then fit the back scattering. When I do that I get a good result. However, after I fit each individual shell and get R and Sigma^2, then I try to combine the shells together. The resultant spectrum does not match the fit. Do I have to combine the shells together after I fit each one individually or it is possible to do each one by its own? __________________________________ Do you Yahoo!? Free Pop-Up Blocker - Get it now http://companion.yahoo.com/

2 1

Re: [Ifeffit] Re: a question about EXAFS fitting result
by SCalvin100＠aol.com 12 Nov '03

12 Nov '03

My two cents (understanding that we have no specifics on Steven's particular sample): This particular comparison to a standard would make me exceedingly nervous as a general rule. Any sample which has a coordination 5/9 of the empirical standard is hardly a minor variation on the standard. And since the DW factor is likely to correlate highly to coordination number for a single-shell fit, part of an apparent change in coordination number might actually be due to a change in DW factor. Again, without knowing the details of the project, or even Bruce's reply as to what happened with the cobalt foil, I highly recommend analyzing more than just the nearest neighbor when trying to determine coordination number. For example, average coordination number for the first shell is theoretically reduced in nanoparticles, but due to other effects this is a highly unreliable measure of particle size. When the effect of scattering off of neighbors beyond the nearest is included, however, Anatoly Frenkel (among others) has demonstrated that particle size can often be determined with reasonable accuracy. --Scott Calvin Sarah Lawrence College In a message dated 11/12/03 8:45:45 AM Eastern Standard Time, ravel(a)phys.washington.edu writes: > I am analyzing cobalt. As I spoke with you before, I got the > coordination number of cobalt foil as around 9 instead of 12. You > explained me why it can happen. What I want to know is If we got > coordination number as 5 for a sample we are interested in and got > the cobalt foil coordination number as 9, can I proportionally > correct the value? (Consider 9 as 12 and multiply 5 by the ratio) Or > just disregard the foil's coordination number? Could you please let > me know what would be the better way to get the correct value? Steven, This is the sort of question for which we created the mailing list, so I am forwarding it and my brief answer there. If you are not already subscribed, you might find it useful to do so. The simple answer is "probably". The point of measuring a standard under identical conditions to the sample is to recognize any systematic effects in the measurement, the smaple, the detectors, or the theory. If all else besides the sample is equal, then you can probably make the argument you suggest above. It will be, of course, incumbant upon you to convince your reader that what you did was reasonable when you publish. You most certainly CANNOT cite "Bruce Ravel, private communication" as your justification!!! That said, if you want more specific help from the crowd on the mailing list, you may wish to provide some more specifics about the details of your problem.

1 0

RE: [Ifeffit] testing ravelware
by Kelly, Shelly D. 12 Nov '03

12 Nov '03

Hi Matt, > Hi Shelly, > > > > Bruce says: > > > P.S. Once again, on the topic of how people can contribute to the > > > ifeffit project without writing code, volunteering > to conceive of > > > a battery of tests and then actually running them would be an > > > excellent contribution. Any takers? > > > > I would think that someone would want to write a perl script to > > execute a bunch of Athena/Artimis commands and then check > the results. > > Then have the script write out a report. (Kind of like what tkperl > > does when you do install the software?) Can Athena/Airtimes > commands > > be executed from a script? If someone was willing to > figure out how > > to do this for one or two of the commands, I would be > willing to extend it to the rest. > > Testing ifeffit commands with the Ifeffit perl module is > definitely possible. That may miss some artemis/athena > capabilities and potential problems, but would still be > useful. You could certainly emulate much of athena's > functionality into perl scripts to do background subtraction, > FFTs, and merging of data with a wide range of parameters and > data sets. > > A script like the simple one below might be pretty good place > to start. (This could be done in languages other than perl > and English). There is also a test.pl with the ifeffit > source perl module (I think it's called t/ifeffit.t in > horae), which mostly tests passing of data between perl and > Ifeffit. Since the script below essentially runs an ifeffit > script, there are several test/example scripts in the > examples/ folder that could be used as the basis of other tests. > > The main difficulty is deciding when the analysis or > calculated values are "right", which makes detecting problems > hard to automate. > > If anyone wants more pointers on how to use the ifeffit from > scripts (perl, python, tcl, ...), please let us know. > > --Matt > > #! /usr/bin/perl > use Ifeffit; > use Ifeffit qw(get_scalar); > > my $xmu_file = "a.xmu"; > my $expected_e0 = 8980.0; > my $toler = 0.5; > > print "Test Finding E0 for $xmu_file: "; > > my $script =<<"END"; > read_data(file = $xmu_file, prefix = my, type = xmu) > pre_edge(my.energy, my.xmu) > END > > $ret = ifeffit($script); # should test $ret for errors. > $e0 = get_scalar("e0"); > print " found $e0, which is "; > > if ( abs($e0 - $expected_e0) le $toler) { > print "ok\n"; > } else { > print "outside of expected range\n"; > } > > ##---- end test_e0.pl This is the kind of script is what I had in mind. As you mentioned this script checks ifeffit directly. I would like to extend it so that Athena is checked. Does anyone know how to do that? This makes me think that if one was cleaver about the way that the test is written that it could be done to check both Athena and/or Ifeffit. That would make the tests more general diagnostic tools. Shelly

5 9