[Ifeffit] Error in second shell fit

[Ivan Stijepovic]

Hi guys!

Just a thought and one question regarding "freeze" option in Athena. Would
it be better to set rmax in Athena to some higher value in the first place,
e.g. 7, and then use "freeze group" option? The error in Artemis would be
avoided and one could still use "freeze". Does it sound right?

On Wed, Feb 20, 2013 at 11:18 PM, Devender <devend at rpi.edu> wrote:

> Hi Bruce,
>
> I tried that quickly, and no more error log! Fitting for second and third
> shells is working. Appreciate your help and going over my files.
>
> Freeze option really helps when I am trying to analyze systematic data
> like doping, where I have added incremental amount of dopants, and want to
> compare them together to notice changes without letting athena vary
> parameters for different scans.
>
> Regards,
> Dev
>
>
> On Wed, Feb 20, 2013 at 4:59 PM, Bruce Ravel <bravel at bnl.gov> wrote:
>
>> On Tuesday, February 19, 2013 11:47:25 AM Devender wrote:
>> > I tried that too, went till 8 A, but it is still showing same error
>> whereas
>> > R effective for second shell paths are 4.4 and 4.7 A. I have also
>> attached
>> > athena file and artemis project file for my data for reference.
>>
>> Dev,
>>
>> I finally got to sit down and look at your problem in detail.  I now
>> appreciate why you are so confused.
>>
>> In Athena, you used the "freeze group" feature.  That's good.  Frozen
>> groups are an excellent way of making sure that you do not
>> accidentally change something you don't want changed.  I am glad you
>> are using that feature of Athena and I encourage you to continue doing
>> so.
>>
>> Unfortunately, in Artemis, I did not take care to unset the flag that
>> freezes a group.  When you attempted to change the value of Rmax for
>> the fit, as Darek, Chris and I were suggesting, it didn't work because
>> I had forgotten to have Artemis unset that flag freezing the data
>> group.  Oops!
>>
>> I have already fixed this problem and this fix will be in the ne4xt
>> release.
>>
>> As the immediate work-around, what you should do is open Athena,
>> untick the "freeze" button for the data you want to analyze, save the
>> Athena project file, then re-import the data into Artemis.
>> Afterwards, I think you will find that changing the Rmax value will
>> have the effect that we were talking about.
>>
>> Thank you for bringing this problem to my attention.  It's a very
>> serious problem that needs to be fixed.  And now it will be!
>>
>> Cheers,
>> B
>>
>>
>>
>> --
>>
>>  Bruce Ravel  ------------------------------------ bravel at bnl.gov
>>
>>  National Institute of Standards and Technology
>>  Synchrotron Methods Group at NSLS --- Beamlines U7A, X24A, X23A2
>>  Building 535A
>>  Upton NY, 11973
>>
>>  Homepage:    http://xafs.org/BruceRavel
>>  Software:    https://github.com/bruceravel
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>
>
>
> --
> Devender
> Graduate Student, Materials Science and Engineering
> Rensselaer Polytechnic Institute, Troy, NY
> Website <https://sites.google.com/site/devendermaun/>
>
>
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>


-- 
Best wishes,
Dr Ivan Stijepović

Department of Materials Engineering
Faculty of Technology
University of Novi Sad
Bul. cara Lazara 1
21000 Novi Sad
Serbia

tel: +381 21 485 3750
fax: +381 21 450 413
e-mail: ivan.stijepovic at gmail.com
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