[Wien] resolution dependent F(HKL)s from lapw3

[Georg Eickerling]

Dear WIEN users,

I noticed a strange behavior of lapw3 which I do not understand:

Take for example a simple diamond case and calculate structure
factors from clmsum, lets say up to sin theta/lambda = 1.0:

    0    0    0   0.0000000       12.0000251726
   -1   -1   -1   0.2427814       -4.6536716863
    0    0   -2   0.2803398        0.0000000000
    0   -2   -2   0.3964603       -3.9459734623
   -1   -1   -3   0.4648909       -2.3988162763
   -2   -2   -2   0.4855627        0.2266152403
    0    0   -4   0.5606796       -3.1297582248
   -1   -3   -3   0.6109864        2.2069300710
    0   -2   -4   0.6268588        0.0000000000
   -2   -2   -4   0.6866894        2.8777607788
   -3   -3   -3   0.7283441        1.9393120414
   -1   -1   -5   0.7283441        1.9663566686
    0   -4   -4   0.7929206        2.6458269883
   -1   -3   -5   0.8292562        1.8056937118
   -2   -4   -4   0.8410193       -0.0171687161
    0    0   -6   0.8410193        0.0000000000
    0   -2   -6   0.8865122        2.4363270068
   -3   -3   -5   0.9191554       -1.6841664183
   -2   -2   -6   0.9297818       -0.0087306004
   -4   -4   -4   0.9711255       -2.2589221048

Repeating this calculation with sin theta/lambda = 1.1 and a diff
with the old hkl will just show the additional reflections as expected:

diff hkl.10 hkl.11
20a21,26
>    -1   -5   -5   1.0010132        1.6970975057
>    -1   -1   -7   1.0010132        1.5391902602
>     0   -4   -6   1.0107794        0.0000000000
>    -2   -4   -6   1.0489354       -2.0944311378
>    -3   -5   -5   1.0766653       -1.4379800081
>    -1   -3   -7   1.0766653       -1.4425910379

Now again repeat the calculation with sin theta/lambda = 1.2:

diff hkl.11 hkl.12
25,26c25,32
<    -3   -5   -5   1.0766653       -1.4379800081
<    -1   -3   -7   1.0766653       -1.4425910379
---
>    -3   -5   -5   1.0766653       -1.4106390375
>    -1   -3   -7   1.0766653       -1.4699320085
>     0    0   -8   1.1213591        1.9443586030
>    -3   -3   -7   1.1473400        1.3618747163
>    -4   -4   -6   1.1558705        0.0030399053
>     0   -2   -8   1.1558705        0.0000000000
>     0   -6   -6   1.1893809        1.7411783356
>    -2   -2   -8   1.1893809       -1.8133181764

What happens here? Why are reflections which were exactly the same
before suddenly different? Why I worry about this is, that if you go
on increasing the resolution, the differences become more severe
than in the example above, i.e. sin theta/lambda = 1.3:

diff hkl.12 hkl.13
21,22c21,22
<    -1   -5   -5   1.0010132        1.6970975057
<    -1   -1   -7   1.0010132        1.5391902602
---
>    -1   -5   -5   1.0010132       -1.5542465484
>    -1   -1   -7   1.0010132        1.5480881986

On the other hand, the differences "converge" for a given reflection
but more and more become "affected",  i.e. sin theta/lambda = 1.8
vs. 1.2:


diff hkl.12 hkl.18
21,22c21,22
<    -1   -5   -5   1.0010132        1.6970975057
<    -1   -1   -7   1.0010132        1.5391902602
---
>    -1   -5   -5   1.0010132       -1.5542465484
>    -1   -1   -7   1.0010132        1.5480881986
25,26c25,26
<    -3   -5   -5   1.0766653       -1.4106390375
<    -1   -3   -7   1.0766653       -1.4699320085
---
>    -3   -5   -5   1.0766653       -1.4379800081
>    -1   -3   -7   1.0766653       -1.4425910379
28c28
<    -3   -3   -7   1.1473400        1.3618747163
---
>    -3   -3   -7   1.1473400       -1.3370357923
31c31
<     0   -6   -6   1.1893809        1.7411783356
---
>     0   -6   -6   1.1893809       -1.8136982305


Looking at the result of a refinement of a structural model against
the different HKLs, the "high resolution version" seems to be
"wrong" compared to the low-res one.

Thank you very much in advance for any comments on this.

regards

Georg Eickerling


-- 
============================
Dr. Georg Eickerling
Universitaet Augsburg
Institut fuer Physik
Lehrstuhl fuer Chemische Physik und Materialwissenschaften
Universitaetsstr. 1
86159 Augsburg

E-Mail:	georg.eickerling at physik.uni-augsburg.de
Phone:	+49-821-598-3362
FAX:	+49-821-598-3227
WWW:	http://www.physik.uni-augsburg.de/cpm/
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