On 03/20/2015 01:57 PM, huyanyun@physics.utoronto.ca wrote:
I feel happy that you still remember that bizarre system which I am still working on. Your brought up a very interesting test to do. I will definitely do this test experiment to see what would happen to the amplitude S02 if the first-shell distance is larger than 3 angstrom. This might take me for a while. I will come back to you after I do it
Well, I've reviewed your CLS proposals at least twice and discussed your problem with you at an XAFS course. Eventually things do stick even in my tiny, little brain :) On this page of the Artemis manual: http://bruceravel.github.io/demeter/artug/extended/qfs.html I explain why the Artemis user should be careful not to misuse the quick first shell tool in Artemis. The bottom line is that unphysical muffin tin radii in the Feff calculation show up in large part as incorrect amplitudes of the calculated chi(k) for the path, as you can see in the second and third figures on that page. In fact, unphysically large muffin tins lead to larger amplitudes, as shown by the red lines It's a little hard to decide exactly how your physical near-neighbor separation of 3.3 A should be related to a Feff calculation that purposefully sets the muffin tins to be loo large, but I think you can see why I'm concerned that this effect might be related to your large fitted S02 values. B -- Bruce Ravel ------------------------------------ bravel@bnl.gov National Institute of Standards and Technology Synchrotron Science Group at NSLS-II Building 535A Upton NY, 11973 Homepage: http://bruceravel.github.io/home/ Software: https://github.com/bruceravel Demeter: http://bruceravel.github.io/demeter/