Re: [Ifeffit] question about sigma2 and atomic distance

I imagine they could, yes. Motivation to do so is another question entirely. Considering myself more of an experienced amateur, and a fan of the Socratic Method, let me ask you a few questions: What do you currently understand about the relationship between two atoms in a material and the mean square relative displacement (i.e. sigma^2) associated with the distance between them? What does it mean to have a mean-square-displacement? ..and then a mean-square-relative displacement? How would correlated, anti-correlated and uncorrelated relative motion affect the msrd? Now extend this thinking to an ensemble of atoms. What might you expect to be the source of a msrd in a perfect crystal at finite temperature? What additional contribution may result from imperfections? On Wed, Jun 7, 2017 at 7:12 PM, Shaofeng Wang wrote:

Dear everyone,

Could experts explain the relationship between sigma2 and atomic distance of same two atoms?

Best regards,

Shaofeng

-------------------------------------- Shaofeng Wang, Ph.D of Geochemistry Environmental Molecular Science Group Institute of Applied Ecology, Chinese Academy of Sciences Shenyang, 110016, China wangshaofeng@iae.ac.cn www.iae.cas.cn

*From:* Shaofeng Wang *Sent:* Friday, June 02, 2017 4:32 PM *To:* XAFS Analysis using Ifeffit *Subject:* [Ifeffit] a question about S02

Hi everyone,

I am fitting a standard material scorodite. The fitting results are pretty good, but the S02 is around 1.2 when the k range = 4-13.5. Is this result reasonable? Please see the attached files.

Best regards,

Shaofeng

-------------------------------------- Shaofeng Wang, Ph.D of Geochemistry Environmental Molecular Science Group Institute of Applied Ecology, Chinese Academy of Sciences Shenyang, 110016, China wangshaofeng@iae.ac.cn www.iae.cas.cn

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