However, I would like to query whether (unlike Rietveld
analysis) this particular implementation is destined to be yet
another obscure occult method of little relevance and little use.
Solid implementations and solid science has the property of
being workable without arbitrary geographical or cultic
limitations.
Does this software require the influences of mystic druids to
successfully operate (in forest groves?) or can mere mortals
interact with this software successfully?
Not having the paper at hand, I am not sure if this code is
written in fortran, C or inscrutable celtic runes. Irrespective
of this, "valid" code is compilable into executables without
compromising the code - and distributable for evaluation and
benefit of the academic community.
Of the many examples of crystallographic software that combines
well considered algorithms with robust useability, the Sirware
suite (Sir97 and EXPO (Extra and Sirpow combined)) would have
to be at or near the top of the list for single crystal and
powder diffraction. This opinion has been obtained not from
listening to the Sirware authors, but chatting to users and
running this "free for academia" software myself.
http://www.ba.cnr.it/IRMEC/SirWare_main.html
CCP14 Automirror:
http://www.dl.ac.uk/CCP/CCP14/ccp/web-mirrors/sirware/IRMEC/SirWare_main.html
Quick Sir97 graphical run through at:
http://www.dl.ac.uk/CCP/CCP14/tutorial/sir97/index.html
It also includes the source code - for those who thought this was no
longer possible.
Lachlan.
PS: While repeating myself from a pervious email, an excellent
introductory book for those who doubt claims on power of genetic
algorithms/A-life algorithms may like to consult:
http://mosaic.echonyc.com/~steven/alife.html
(Steven Levy - Artificial Life - Quest for a new Creation)
More self-citation follows that the CCP14 auto-mirroring
area at: http://www.dl.ac.uk/CCP/CCP14/mirror/mirror.htm#alife
has an archive of genetic algorithms and Artificial-life resources
as examples of how this area is developing outside crystallography.
It would be nice to have tangeable/reproducable examples of
examples within crystallography.
People ignoring this algorithmic area will no doubt be
communing with the dinosaurs in the not too distant future(?)
>
> Some of you may remember a small "discussion" on
> this mailing list earlier in the year on the subject
> of using integrated intensities for structure solution
> via global optimisation. For those of you who were
> left with some doubts concerning the usefulness of
> integrated intensities in this regard, we'd like to draw
> your attention to our latest paper.
>
> "Routine determination of molecular crystal structures from
> powder diffraction data"
> William I. F. David, Kenneth Shankland and Norman Shankland
> Chemical Communications, 1998, Vol. 8,931-932
>
> This demonstrates the structure solutions of three previously
> unknown crystal structures by the application of simulated annealing
> using extracted intensities. Of note is
>
> - the size and internal flexibility of the structures (up to 10
> internal torsions)
> - multiple fragment movement
> - the speed with which the solutions were obtained
> - the accuracy of the answers, given the limited data range used
>
> The picture of the powder solution of capsaicin versus the single
> crystal structure of capsaicin should interest those who feel it
> is not possible to refine close to an answer using extracted
> intensities. And just in case you're saying "ah, so they knew
> the single crystal structure", no we didn't. We just measured
> it later to head off the cynics who would not believe that the
> powder structure was correct......
>
> Cheers,
>
> Kenneth
>
> ----------------------------------
> Dr. Kenneth Shankland,ISIS Facility,Rutherford Appleton Laboratory
> Chilton,Didcot,Oxon OX11 0QX,United Kingdom
> Tel : +44 1235 44 6381
> Fax : +44 1235 44 5720
> E-Mail: k.shankland@rl.ac.uk
> Date: 21-Apr-98
> Time: 19:23:40
> ----------------------------------
>
>
> --
> Dr. Kenneth Shankland,Building R3,ISIS Facility,Rutherford Appleton Laboratory
> Chilton,Didcot,Oxon OX11 0QX,United Kingdom
> Tel : +44 1235 44 6381 Fax : +44 1235 44 5720
> Email : k.shankland@rl.ac.uk
>
-- Lachlan M. D. CranswickCollaborative Computational Project No 14 (CCP14) for Single Crystal and Powder DiffractionDaresbury Laboratory, Warrington, WA4 4AD U.KTel: +44-1925-603703 Fax: +44-1925-603124 E-mail: l.cranswick@dl.ac.uk Ext: 3703 Room C14CCP14 Webpage (Under heavy reconstruction): http://www.dl.ac.uk/CCP/CCP14/
Crystallographic Nexus Virtual Web and Internet on CD-ROM: http://www.unige.ch/crystal/stxnews/nexus/index.htm
Personal Crystallographic WWW: http://www.unige.ch/crystal/stxnews/stx/volnteer.htmCommission on Powder Diffraction, Quantitative Phase Analysis Round Robin: http://www.dl.ac.uk/SRS/XRD/IUCR/QARR/Society of Crystallographers in Australia (SCA): http://www.sca.asn.au/Australasian Web Publishers Association: (AWPA): http://www.awpa.asn.au/Australian X-ray Analytical Association (AXAA): http://www.latrobe.edu.au/www/axaa/