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

choosing k-weight
by Peter Southon 20 Feb '04

20 Feb '04

Dear Ifeffiters, I'm wondering what principles you have to determine the appropriate k-weight to use for FTs. Until now I've used guidelines from a textbook by Teo, based on the Z of the backscattering atoms: Z > 57; kw = 1 57 > Z > 36; kw = 2 Z < 36; n = 3 Of course you can have different backscatterers around your absorber - I've got C, N and Pt! Are there any other rules you follow? Thanks very much in advance! Peter Peter Southon Post Doctoral Fellow School of Chemistry University of Sydney NSW 2006, Australia +61 2 9351 4425

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Re: [Ifeffit] choosing k-weight
by SCalvin100＠aol.com 20 Feb '04

20 Feb '04

Peter, Of course, the bottom line is that the k-weight shouldn't affect the values of the parameters Ifeffit finds. If it does, it's a sign that the parameters should not be trusted. Often, this happens when the k-range chosen to fit is inappropriate (extends up into a range where the data is dominated by noise, down into a range where the background is poorly chosen, or across a small edge due to a contaminant, for example). I always test my "final" fits at all three k-weights separately to make sure the values of the parameters stay fairly stable. --Scott Calvin Sarah Lawrence College

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RE: [Ifeffit] choosing k-weight
by Kelly, Shelly D. 20 Feb '04

20 Feb '04

> Dear Ifeffiters, > > I'm wondering what principles you have to determine the appropriate > k-weight to use for FTs. Until now I've used guidelines from > a textbook by > Teo, based on the Z of the backscattering atoms: > Z > 57; kw = 1 > 57 > Z > 36; kw = 2 > Z < 36; n = 3 > > Of course you can have different backscatterers around your > absorber - I've > got C, N and Pt! Are there any other rules you follow? > > Thanks very much in advance! > > Peter Hi Peter, I have found it very useful to use all three kweights, simultaneously. You can really cut down of the correlation between the different EXAFS parameters by doing so. This paper shows a model that was fit to the data with all three kweights. Geo. Cosmo Acta 66(22): pp 3855-3871, November 2002. I have been thinking about putting together an Artemis project file that shows how to do this. If there is interest, I would be willing. Shelly

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Re: IFEFFIT updater problem
by Matt Newville 19 Feb '04

19 Feb '04

Hi Jeff, On Wed, 18 Feb 2004, Jeffrey Catalano wrote: > > The IFEFFIT updater is behaving badly. Everytime I start an IFEFFIT group > program, it wants to download the same two updates. I've installed them > three times now (remembering to run the make bat thingy each time). Any > ideas if the problem is with my computer or with the updater? Other than > that everything works wondefully! Hmm, that seems weird. Here's what is supposed to happen with the updater (and I hope you mind me sending this on to the mailing list -- if the problem happens for you, it will probably happen for someone else, and the updater isn't very well documented), and a way that should be able to work around it -- you can skip to the end if you like ;). When the applications apt, artemis, athena, gifeffit, ifeffit, sixpack, and tkatoms run (from the batch files, desktop icon, or start menu), the updater is run before the main application is run. The updater reads two files: C:\Program Files\Ifeffit\updates\updater.ini C:\Program Files\Ifeffit\updates\updater.dat updater.dat holds the current 'local update level' on your machine, which is just a 3 digit number, like 003 or 005. updater.ini holds the time of the last "real check for updates" and how long to wait until the next update should be done. If the last real check was within the last 24hours, the updater stops right there. Actually, the time to wait until the next real check can be set longer with the 'Do not remind me again until' list in the main updater GUI. If it's past the time to do a "real check for updates", the updater fetches the current 'available update level' from the cars webpage: http://cars9.uchicago.edu/ifeffit/updates/update.dat, which currently reads '005'. If it can't reach this web page and read this file in 15seconds, the updater stops. If the 'local updater level' is equal to the 'available update level', you are up to date and the updater stops. If the 'local updater level' is less than the 'available update level', a GUI pops up, and you are told that there are update(s) to install, and asked if you'd like to install them. If you approve, the updates are downloaded one by one and installed. The update packages are all zip files, named as http://cars9.uchicago.edu/ifeffit/updates/ifup_XXX.zip for update level=XXX. The progress of the download and unpacking should be shown in the updater GUI. These updates are unpacked relative to the main Ifeffit directory, typically C:\Program Files\Ifeffit. Each of the updates includes, the file 'updates\updater.dat' to have the 'current update level'. So, if the update ifup_005.zip was installed, updates\updater.dat should say '005', and the updater shouldn't run again until I set the update level on the web page to 006. OK, that's what is supposed to happen. If that hasn't happened and updates\updater.dat does not say '005', a simple solution should be to edit it (notepad, whatever) to say 005 in the first line. I'd be interested to hear if other people are having this problem. Cheers, --Matt PS: a small problem can occur if the updater.exe program itself needs to be updated, as an executable program currently in use cannot be overwritten. So any new updater.exe is written to the 'updates' directory, and you are told to run make_bats.exe. Then make_bats.exe checks for an updater.exe in the updates directory and moves it to the main Ifeffit directory.

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Ifeffit updater
by Peter Southon 19 Feb '04

19 Feb '04

Hello, I'm a little confused about the role of the Ifeffit updater - does it cover just Ifeffit, or Athena/Artemis as well? It has updated my Ifeffit to v1.2.5 fine, but my version of Artemis is still 0.6.009, when Bruce's web page says that 0.6.010 was released last year. Do we have to update Athena/Artemis separately, and if so is there a way for PC users to do this without downloading the entire Ifeffit package again? Thanks, Peter Peter Southon Post Doctoral Fellow School of Chemistry University of Sydney NSW 2006, Australia +61 2 9351 4425

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finding stuff in the archives
by Bruce Ravel 19 Feb '04

19 Feb '04

Hi folks, A while back there was some discussion about indexing the archive of the mailing list. Still a good idea, but I wanted to suggest a user-land solution to the problem. It is possible to find stuff on the archive using Google. This shouldn't be a surprise -- I, for one, cannot imagine how I ever knew anything in the years B.G. (before Google). Try going to http://www.google.com/ and entering this as your search: site:millenia.cars.aps.anl.gov clamp This will return a hit for every entry in the archive that discusses spline clamps. In my last posting to the mailing list, I did this google search: site:millenia.cars.aps.anl.gov imaginary energy The "site:" directive tells google to restrict its search to pages that match that site. I learned about this trick from the book Google Hacks http://www.amazon.com/exec/obidos/ASIN/0596004478/qid=1077200261/sr=2-1/ ref=sr_2_1/002-8270889-0247203 HTH, B -- ********* PLEASE NOTE MY NEW PHONE, FAX, & ROOM NUMBERS ****************** Bruce Ravel ----------------------------------- ravel(a)phys.washington.edu Code 6134, Building 3, Room 405 Naval Research Laboratory phone: (1) 202 767 2268 Washington DC 20375, USA fax: (1) 202 767 4642 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/

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imaginary energy correction
by Stanislav Stoupin 19 Feb '04

19 Feb '04

Hello all, I would appreciate if somebody could explain the meaning of imaginary energy correction (Ei parameter). So far I have not found any description of the parameter. If anyone knows of any example on how to use it, please let me know. Stanislav

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Sourceforge problem
by Peter Southon 18 Feb '04

18 Feb '04

Hello again, I've been having problems using Sourceforge.net to download Ifeffit. I've mainly been trying to use the Flow Australian mirror, but none of them seem to be responding, returning an Error (110) "Connection timed out" message. Have other people been having this problem? (or it might be something funny at my end) Meanwhile I'll just use the cars sever. Cheers, Peter Peter Southon Post Doctoral Fellow School of Chemistry University of Sydney NSW 2006, Australia +61 2 9351 4425

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THANKS AGAIN
by doug pease 16 Feb '04

16 Feb '04

Thanks again to Matt for fixing the graphical screen problem. To Matt and Bruce.....this is great!! Cheers, Doug Pease

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Re: merging
by dmc＠pdx.edu 12 Feb '04

12 Feb '04

Bruce, I succeeded in merging the k-plots of several files in Athena, but failed at opening the data and graphing it in Artemis for fitting purposes. Is this merging function purely for use in Athena? You'd made it sound like I could use that data for fitting. If it is possible to export the merge to Artemis for a fit, let me know how. Thanks, Dan

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