Dear Rietveld Users,
I have a question on the TOPAS usage of a rigid body
(as a Z-matrix). Assuming the information:
Space group P 1 21/c 1
Lattice Parameters a = 15.7840
b = 5.3100
c = 9.3740
beta = 93.36
Let us say we have located a phenyl ring C1-C6 --- the
fractional coordinates obtained from FOX, DASH or any
other str-solution software --- and I get the
corresponding rigid Z-matrix:
'--------------------------------------------
site C1 num_posns 4 x 0.33100 y 0.95910 z 0.40590 occ
C 1 beq 1
site C2 num_posns 4 x 0.25560 y 0.82610 z 0.39900 occ
C 1 beq 1
site C3 num_posns 4 x 0.33790 y 1.15770 z 0.49730 occ
C 1 beq 1
site C4 num_posns 4 x 0.19000 y 0.88300 z 0.48260 occ
C 1 beq 1
site C5 num_posns 4 x 0.27620 y 1.22350 z 0.58350 occ
C 1 beq 1
site C6 num_posns 4 x 0.20100 y 1.08750 z 0.57730 occ
C 1 beq 1
'----------- Rigid Defined
rigid
z_matrix C1
z_matrix C2 C1 1.382
z_matrix C3 C1 1.359 C2 117.578
z_matrix C4 C2 1.368 C1 122.597 C3 358.2
z_matrix C5 C3 1.347 C1 123.039 C2 2.3
z_matrix C6 C5 1.388 C3 119.106 C1 358.4
'--------------------------------------------
Point_for_site(C1@ 0, @ 0, @ 0)
Rotate_about_axies (@ 1, @ 2, @ 3)
Translate (@ 0.19000, @ 0.88300, @ 0.48260)
'--------------------------------------------
The Question:
---------------
I can understand the values for the Point_for_site and
Translate. But, I am not sure how I can derive the
values for the Rotate_about_axies for the molecule
(without doing the structure solution again using
TOPAS)!? It would be very helpful if someone can help
me out the way to find these values.
Thank you very much for your time in advance.
Bhuv
Texas A&M University
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