On Tuesday 08 May 2007, Jun Lin wrote:
I have read some references of Kelly Shelly, and I have got some idea of how to construct a structure without difinite crystalline structure. But when I try to apply to my own question, meet some difficulties.
In my case, four nitrogen atoms is surrounding a iron atom. So I use OVERLAP and SS card as to define such system as described in the FEFF manual:
Jun, Just to reiterate, neither I nor Shelly would advocate your approach. (I think I can speak for her on this topic. I'm sure she'll let me know if I am mistaken! ;-) ) In my earlier email I was trying to suggest that you use the ATOMS list in Feff on a related compound and attempt to model your data in terms of that related compound. That is certainly what Shelly has done in any of her papers that you might have read. There are a number of reasons I suggest this, mostly having to do with approaching the problem with as much flexibility as possible. For instance, the OVERLAP/SS use of Feff means that you cannot (easily) consider multiple scattering contributions in your fit. It is also considerably harder to interpret your fitting parameters in terms of the 3D structure of the material you are analyzing when you use the OVERLAP/SS approach in Feff. The main reason I recommend against the OVERLAP/SS approach is that that's not how Artemis works. Artemis expects you to use an ATOMS list. Scott Calvin's Artemis tutorial at http://cars9.uchicago.edu/iffwiki/HoraeSoftware#contrib is a good way to learn how Artemis works. B -- Bruce Ravel ---------------------------------------------- bravel@anl.gov Molecular Environmental Science Group, Building 203, Room E-165 MRCAT, Sector 10, Advance Photon Source, Building 433, Room B007 Argonne National Laboratory phone and voice mail: (1) 630 252 5033 Argonne IL 60439, USA fax: (1) 630 252 9793 My homepage: http://cars9.uchicago.edu/~ravel EXAFS software: http://cars9.uchicago.edu/~ravel/software/