Applicable scope of delr=alpha*reff

older
Reference spectra for brookite,...

woschangqiang

2 Aug 2016 2 Aug '16

10:27 a.m.

Hi, everyone. delr=alpha*reff is very powerful in the fit of cubic system. And I want to know whether this function can be used in other crystal system. Thank for your patient answer.

Attachments:

attachment.html (text/html — 348 bytes)

Show replies by date

Bruce Ravel

2 Aug 2 Aug

12:40 p.m.

On 08/02/2016 06:27 AM, woschangqiang wrote:

...

Hi, everyone. delr=alpha*reff is very powerful in the fit of cubic system. And I want to know whether this function can be used in other crystal system. Thank for your patient answer.

http://bruceravel.github.io/demeter/documents/Artemis/extended/delr.html -- Bruce Ravel ------------------------------------ bravel@bnl.gov National Institute of Standards and Technology Synchrotron Science Group at NSLS-II Building 743, Room 114 Upton NY, 11973 Homepage: http://bruceravel.github.io/home/ Software: https://github.com/bruceravel Demeter: http://bruceravel.github.io/demeter/

If you think it’s plausible that the crystal is expanded or contracted isotropically and homogeneously, then it’s a model worth trying. It’s usually my first model for fitting just about any crystalline material. Often, the resulting fits are not good, and then I have to try other models. But sometimes, particularly when the differences from my model structure are small, it works fairly well. In terms of the criteria I described herehttps://www-ssrl.slac.stanford.edu/conferences/workshops/srxas2011/presentat... and elsewhere, it has the advantage of “simplicity” under criterion 4. Whether or not it produces a good fit under the other criteria is, of course, something that you have to find out for each system. —Scott Calvin Sarah Lawrence College On Aug 2, 2016, at 6:27 AM, woschangqiang mailto:woschangqiang@126.com> wrote: Hi, everyone. delr=alpha*reff is very powerful in the fit of cubic system. And I want to know whether this function can be used in other crystal system. Thank for your patient answer. _______________________________________________ Ifeffit mailing list Ifeffit@millenia.cars.aps.anl.govmailto:Ifeffit@millenia.cars.aps.anl.gov http://millenia.cars.aps.anl.gov/mailman/listinfo/ifeffit Unsubscribe: http://millenia.cars.aps.anl.gov/mailman/options/ifeffit

woschangqiang

3 Aug 3 Aug

12:19 p.m.

Than you very much for the provided link from Bruce Ravel and answer from Scott Calvin. At 2016-08-02 20:58:36, "Scott Calvin" wrote: If you think it’s plausible that the crystal is expanded or contracted isotropically and homogeneously, then it’s a model worth trying. It’s usually my first model for fitting just about any crystalline material. Often, the resulting fits are not good, and then I have to try other models. But sometimes, particularly when the differences from my model structure are small, it works fairly well. In terms of the criteria I described here and elsewhere, it has the advantage of “simplicity” under criterion 4. Whether or not it produces a good fit under the other criteria is, of course, something that you have to find out for each system. —Scott Calvin Sarah Lawrence College On Aug 2, 2016, at 6:27 AM, woschangqiang wrote: Hi, everyone. delr=alpha*reff is very powerful in the fit of cubic system. And I want to know whether this function can be used in other crystal system. Thank for your patient answer. _______________________________________________ Ifeffit mailing list Ifeffit@millenia.cars.aps.anl.gov http://millenia.cars.aps.anl.gov/mailman/listinfo/ifeffit Unsubscribe: http://millenia.cars.aps.anl.gov/mailman/options/ifeffit

Jasen Vita

5:40 p.m.

Yeah, thanks bruce and Scott. It's been a long time since I've looked at and done synchrotron science, and today just decided what the heck, let's read some of what's going on in the Ifeffit mailing list. Just a friendly stop by from a guy that spent a lot of time in college during the summers trying to figure this stuff out, and noticing strange how after several years, I actually understand the information provided by Bruce and Scott much better now than I did when I was actually doing this kind of research. Happy researching to all. -- Jasen Vita, Sarah Lawrence Alum On Wed, Aug 3, 2016 at 5:19 AM, woschangqiang wrote:

...

Than you very much for the provided link from Bruce Ravel and answer from Scott Calvin.

At 2016-08-02 20:58:36, "Scott Calvin" wrote:

If you think it’s plausible that the crystal is expanded or contracted isotropically and homogeneously, then it’s a model worth trying. It’s usually my first model for fitting just about any crystalline material. Often, the resulting fits are not good, and then I have to try other models. But sometimes, particularly when the differences from my model structure are small, it works fairly well.

In terms of the criteria I described here https://www-ssrl.slac.stanford.edu/conferences/workshops/srxas2011/presentat... and elsewhere, it has the advantage of “simplicity” under criterion 4. Whether or not it produces a good fit under the other criteria is, of course, something that you have to find out for each system.

—Scott Calvin Sarah Lawrence College

On Aug 2, 2016, at 6:27 AM, woschangqiang wrote:

Hi, everyone. delr=alpha*reff is very powerful in the fit of cubic system. And I want to know whether this function can be used in other crystal system. Thank for your patient answer.

_______________________________________________ Ifeffit mailing list Ifeffit@millenia.cars.aps.anl.gov http://millenia.cars.aps.anl.gov/mailman/listinfo/ifeffit Unsubscribe: http://millenia.cars.aps.anl.gov/mailman/options/ifeffit

_______________________________________________ Ifeffit mailing list Ifeffit@millenia.cars.aps.anl.gov http://millenia.cars.aps.anl.gov/mailman/listinfo/ifeffit Unsubscribe: http://millenia.cars.aps.anl.gov/mailman/options/ifeffit

3016

Age (days ago)

3017

Last active (days ago)

List overview

Download

4 comments

4 participants

participants (4)

Bruce Ravel
Jasen Vita
Scott Calvin
woschangqiang