[Ifeffit] Fwd: FEFF trouble help me please !!!!
bravel at bnl.gov
Tue Jul 7 16:00:55 CDT 2015
I want to remind everyone that it is important to use the mailing
list. I do not feel that I am obligated to answer questions about the
software that come to me by any other channel, particularly when I do
not have a personal relationship with the person asking the question.
That said, I am forwarding this fellow's question to the mailing list
and providing an answer.
Thitipong, this is a case of GIGO.
According to Acta Cryst. (1972). B28, 3102-3103 (the reference I found
The crystal structure of chromium carbide, C r 2 3 C 6 , has
been described as cubic, space group Fm3m, 4Cr (I) in (a)
(000), 8Cr (II) in (c) (l-lq:), 48Cr (III) in (h) (Oxx), x=
0.165, 32Cr (IV) in (f) (xxx), x=0.385, 24C in (e) (x00),
x=0-275 (Westgren, 1933) on the basis of X-ray single
crystal and powder diffraction data. We have confirmed
this structure and determined the atom positions more
precisely by a neutron diffraction study of a powder sample.
Using those coordinates, I have no problem running atoms and feff.
The structure is a bit strange -- I guess this is more like a metal
than a carbide -- but it seems consistent with the paper after a
According to http://www.crystallography.net/cod/1009019.html, the
space group for Cr7C3 is P M C N. Atoms and feff run fine with this
Some hints on asking questions that so you'll get the answers you are
-------- Forwarded Message --------
Subject: FEFF trouble help me please !!!!
Resent-Date: Fri, 3 Jul 2015 04:25:57 +0000
Resent-From: bruce.ravel at nist.gov
Date: Fri, 3 Jul 2015 11:33:12 +0700
From: Thitipong Po-Kloy <thitipong_37 at hotmail.com>
To: bruce.ravel at nist.gov <bruce.ravel at nist.gov>
Hi Bruce ,
My name is Thitipong . I have trouble about FEFF program and believes
you can help me.
Now I am doing "XANES simulation" Cr23C6 and Cr7C3 .
So , when I run FEFF program - it report TWO ATOMS VERY CLOSE TOGETHER .
How can I fix it ?
This it Data of atom Cr23C6
title name : Cr23C6
title formula : Cr23C6
space F M 3 M
a=10.6599 b=10.6599 c=10.6599
rmax = 10
Cr 0 0 0 Cr1
Cr 0.25 0.25 0.25 Cr2
Cr 0.385 0.385 0.385 Cr3
Cr 0 0 0.340 Cr4
C 0.276 0.276 0.276 C1
title name : Cr7C3
title formula : Cr7C3
space P M C M
a=7.0149 b=12.1530 c=4.5320
rmax = 10 rpath=6
Cr 0.064 0.811 0.056 Cr1
Cr 0.250 0.626 0.057 Cr2
Cr 0.250 0.206 0.250 Cr3
Cr 0.250 0.416 0.261 Cr4
Cr 0.065 0.021 0.250 Cr5
C 0.250 0.562 0.459 C1
C 0.029 0.342 0.028 C2
If there is any other way please let me know.
Thank You ,
Bruce Ravel ------------------------------------ bravel at bnl.gov
National Institute of Standards and Technology
Synchrotron Science Group at NSLS-II
Upton NY, 11973
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