[Cod-bugs] Querying COD

[Saulius Gražulis]

Dear Randy,

On 2017-09-21 16:59, Randy Williams wrote:
> I would like to find information on how to look up diffraction
> information (d-spacings and relative intensities) through querying the
> COD. I am attempting to construct some custom search match software for
> my lab but I am unable to locate diffraction data in the COD. Please
> advice when convenient.

Diffraction data in COD is in the hkl/ tree:

http://www.crystallography.net/cod/hkl/

it can also be found in the appropriate Subversion repository branch.
These are experimental Fobs data, whenever authors have provided them;
they are not available for all structures.

The d-spacings are easily calculated from the unit cell data, we do not
provide them. Unit cell is specified in each coordinate and Fobs (.hkl)
file. Calculating relative intensities is more tricky, we do not have
them on-line but one can do that by appropriate summation of atomic
structure factors or by FFT.

I would recommend you some text on crystallographic computing, e.g. C.
Giaccovazzo "Fundamentals of Crystallography" is pretty advanced but
will answer all (or most) of your questions
(https://global.oup.com/academic/product/fundamentals-of-crystallography-9780199573660?cc=lt&lang=en&).

Hope this helps.

Sincerely,
Saulius

-- 
Dr. Saulius Gražulis
Vilnius University Institute of Biotechnology, Saulėtekio al. 7
LT-10257 Vilnius, Lietuva (Lithuania)
fax: (+370-5)-2234367 / phone (office): (+370-5)-2234353
mobile: (+370-684)-49802, (+370-614)-36366