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Re : [sdpd] On Crystallography Open Database entries
>In the second
>case, altough I do have the complete crystal data, but I do not know how
>to convert a *.pcr file to a CIF file. Please let me know, and I shall try
>to upload them in future.
About CIFs and the Rietveld program FULLPROF : the CIFs will
be built by using RPA = -1 (then edit and complete the CIFs with author
names, chemical formula, and other details you may consider as essential,
including the complete reference if any).
>I still feel handicapped on how to
>create a CIF file when I have just the data (be it in a database or in
>published literature) and not a CIF file. It would be quite helpful if you
>let us (people like me) know it.
I must agree that CIFs are as opaque as the language for
programming MS Windows...
One simple way for obtaining a CIF is to build first an "improved REF file"
described at : http://www.crystallography.net/ref.html
There is then a small software (REF2CIF) able to transform a REF file
into a CIF : http://www.crystallography.net/ref2cif.zip
Example of a REF file :
================================================
C. Feldmann, M. Jansen, To the knowledge of cis-sodium hyponitrite, Z. Anorg. Allg. Chem. 623 (1997) 1803-1809.
Na2 N2 O2
5.107 9.211 6.159 90. 97.91 90.
P21/c
Na1 4 e 0.3206 0.4389 0.7177 1. 3.8
Na2 4 e 0.2176 0.7512 0.5568 1. 4.5
N1 4 e 0.0957 0.4310 0.2519 1. 3.9
N2 4 e 0.2065 0.3335 0.1699 1. 4.0
O1 4 e 0.2321 0.5559 0.3274 1. 4.5
O2 4 e 0.4763 0.3518 0.1516 1. 3.1
label mult Wyck. x y z occup B-or-U-iso
(do not provide that final line).
===================================================
Mult + Wyck. correspond to the multiplicity and Wyckoff letter of
the position considered. If you do not have time to give these
parameters, then put a ? character (as well as for the atom occupancy
factor and thermal parameter) :
Na1 ? ? 0.3206 0.4389 0.7177 ? ?
The corresponding CIF as built by REF2CIF is the following :
=====================================================
data_new7000001
_publ_section_title
;
C. Feldmann, M. Jansen, To the knowledge of cis-sodium hyponitrite,
Z. Anorg. Allg. Chem. 623 (1997) 1803-1809.
;
_chemical_formula_sum 'Na2 N2 O2'
_cell_length_a 5.1070
_cell_length_b 9.2110
_cell_length_c 6.1590
_cell_angle_alpha 90.000
_cell_angle_beta 97.910
_cell_angle_gamma 90.000
_cell_volume 286.97
_symmetry_space_group_name_H-M 'P21/c'
loop_
_atom_site_label
_atom_site_symmetry_multiplicity
_atom_site_Wyckoff_symbol
_atom_site_fract_x
_atom_site_fract_y
_atom_site_fract_z
_atom_site_occupancy
_atom_site_Uiso_or_Biso
Na1 4 e 0.3206 0.4389 0.7177 1. 3.8
Na2 4 e 0.2176 0.7512 0.5568 1. 4.5
N1 4 e 0.0957 0.4310 0.2519 1. 3.9
N2 4 e 0.2065 0.3335 0.1699 1. 4.0
O1 4 e 0.2321 0.5559 0.3274 1. 4.5
O2 4 e 0.4763 0.3518 0.1516 1. 3.1
=====================================================
The whole reference is inserted into the _pub_section_title_
but who cares ?-). The ENCIFER software can read it.
http://www.ccdc.cam.ac.uk/prods/encifer/
Note that ENCIFER is a CIF editor and visualizer.
The COD is searching for new advisory board members
from various countries (including those not engaged with IUCr).
No duty, no reward, just for doing what you want to do for the COD.
Still no representative (Hareesh Rajan is in the USA) in India Chandan,
it is up to you. But see first if you agree with the COD policy at :
http://www.crystallography.net/cod.pdf
Armel
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