[Ifeffit] Errors from Webatoms?

Feng Wang fwang at phys.ualberta.ca
Sat Feb 18 01:27:42 CST 2006


Hi everyone:

I used WEBATOMS(version 1.8), to calculated the feff.inp for Si-K of 
alpha-SiO2 (quartz phase), using the crystal structure (as listed below) 
from Wyckoff's Crsytal Structures(P312-313), however, I could not get 
correct atomic configuration, such as,  I did not get the tetrahedron (of 4 
nearest neighboring oxygen atoms), I got two n.n. oxygen atoms only, please 
refer to the results on the bottom.
As suggested by Dr. Ravel, I tried the atoms in Artemis, but still I could 
not get correct feff.inp.Would you please help me to check and suggest, 
thank you so much.

Best regards,

Feng 

alpha-SiO2 crystal structure (from Wyckoff's book):  

hexagonal, a=4.91304, c=5.40463, space group: p3121 (#152). Si (3a): (-u,-
u,1/3), (u,u,0) (0,u,2/3); O: (6c): (x,y,z), (y-x, -x, z+1/3), (-y, x-y, 
z+2/3), (x-y, -y,-z), (y,x,2/3-z), (-x,y-x,1/3-z). In which, u(si)=0.465, 
x=0.415, y=0.272, z=0.120. 

According to it, I used the input for WEBATOMS: 
Space group: p3121
OUTPUT type: feff8.inp
Edge: K
shift: 0 0 0 
A=4.91304, c=5.40463
Crystallographic Sites: Si (-0.465 -0.465, 1/3) O (0.415, 0.272, 0.12). 

And I got the atomic configuration in feff.inp as below:

 ATOMS                          * this list contains 449 atoms
 *   x          y          z      ipot  tag           distance
    0.00000    0.00000    0.00000  0    Si            0.00000     0
   -0.51058   -0.99735   -1.15297  2    O             1.60771     1
    0.21274    1.45917   -0.64854  2    O             1.61091     2
    0.00000    0.00000    1.80158  1    Si            1.80158     3
   -2.27633    0.97033    0.00004  1    Si            2.47451     4
    1.97849   -1.48619    0.00004  1    Si            2.47451     5
    0.82118   -2.40002    0.64857  2    O             2.61822     6
   -1.11902    0.05650   -2.45008  2    O             2.69412     7
    0.82118    2.51302    0.64857  2    O             2.72218     8
   -1.66789    1.91117    1.15301  2    O             2.78637     9
    1.37005   -0.54535    2.45012  2    O             2.85964    10
    2.58693   -0.54535    1.15301  2    O             2.88428    11
   -2.27633    0.97033   -1.80153  1    Si            3.06084    12
   -0.29784    2.45652   -1.80153  1    Si            3.06083    13
    1.97849   -1.48619   -1.80153  1    Si            3.06083    14
   -0.29784   -2.45652   -1.80153  1    Si            3.06083    15
   -0.29784    2.45652    1.80154  1    Si            3.06084    16
   -0.29784   -2.45652    1.80154  1    Si            3.06084    17
   -1.11902    0.05650    2.95455  2    O             3.15987    18
    1.37005   -0.54535   -2.95451  2    O             3.30206    19
   -3.43364    0.05650    0.64857  2    O             3.49481    20
    0.21274   -3.45387   -0.64854  2    O             3.52066    21
    0.00000    0.00000   -3.60305  1    Si            3.60305    22
   -1.66789   -3.00187    1.15301  2    O             3.62250    23
    1.97849    3.42685    0.00004  1    Si            3.95698    24
   -0.51058    3.91569   -1.15297  2    O             4.11372    25
    3.74424    1.45917   -1.15297  2    O             4.18065    26
   -4.04208   -0.99735   -0.64854  2    O             4.21352    27
   -2.88477    1.91117    2.45012  2    O             4.23999    28
    3.95698    0.00000   -1.80153  1    Si            4.34778    29
    1.97849    3.42685   -1.80153  1    Si            4.34778    30
    3.95698    0.00000    1.80154  1    Si            4.34779    31
   -0.29784    2.45652   -3.60309  1    Si            4.37098    32
   -0.29784   -2.45652   -3.60309  1    Si            4.37098    33
   -2.27633    0.97033    3.60310  1    Si            4.37099    34
   -0.29784    2.45652    3.60310  1    Si            4.37099    35
    1.97849   -1.48619    3.60310  1    Si            4.37099    36
   -0.29784   -2.45652    3.60310  1    Si            4.37099    37
   -0.51058   -0.99735    4.25166  2    O             4.39682    38
   -2.88477    1.91117   -2.95451  2    O             4.55012    39
   -2.27633   -3.94271    0.00004  1    Si            4.55265    40
    4.46756   -0.99735   -0.64854  2    O             4.62325    41

 


==================================
Feng Wang
fwang at phys.ualberta.ca
Electron Microscopy Group
Department of Physics
University of Alberta
=========================================================



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