Image (Flash not used so as not to distract the presenters)
Description
- BCA Biological Group Prize (photo taken by Kate Crennell)
- BCA Biological Group Prize (photo taken by Kate Crennell)
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(BCA (British Crystallographic Association) SPRING MEETING 2000, 3rd to 5th April, 2000, Heriot-Watt University, Edinburgh. (Abstracts viewable at: http://www.isis.rl.ac.uk/BCA2000/)) Tuesday 4th April 2000, 9.00 CCG workshop: Software demonstrations on recent developments in software for chemical crystallography (Chaired by Simon Parsons of Edinburgh University)
A possibly inaccurate/biased(?) summary of what went on in the session.(Corrections Accepted. It should be noted that tutorials on most of the mentioned/related software are available from the CCP14 site. Photos on this page can be freely copied if wanted)
Paul Buerskens (with Bob Gould
operating the PC Computer) gave a live demonstration of
Dirdif 2000 - structure
solution using Patterson methods, fragment searching methods and difference direct methods.
The DDFLEX intra-fragment flexibility option was also demonstrated (Dirdif 2000 with DDFLEX not
yet released - please be patient). From memory, George Sheldrick mentioned it was easy to see that DOS/Windows
was being used for the demonstration machine as the system had to be rebooted half way through the demonstration.
(was actually a crash in the "microemacs" editor that caused this - not DIRDIF).
Chris Gilmore
gave a live demonstration of the commercial
Maxus for UNIX software. This links to
a variety of structure solving and building options. Automatic structure solution and refinement
as well as overlapping 3D structure plots with 3D Fourier maps were some of the features explored.
George Sheldrick gave a talk about Shelxd
for structure solution of large structures (not yet released - enable "please be patient mode").
Elaboration was made on the use of "random omitting" of 30% of the atoms as part of an effective search algorithm;
as well as the nuances of solving of large structures using available algorithmic options.
David Watkin gave a talk and live demonstration about the philosophy and functionality
behind the latest Crystals for Windows. With the emphasis
on also allowing the chemist to perform high quality structure solution and
refinement. (Though with the institute's expert crystallographer being
accessible to sort out any specialised problems prompted by warnings from Crystals).
Ton Spek gave a set of examples and live
demos on Platon/System S
for: validation, as well as some of the crystallographic tools it contains.
Ton also demonstrated the NQA (no questions asked) option to automatically
solve and refine a structure. System S links to Shelx97/86, Sir97, Dirdif 99.2
and Crunch for solving structures and EXOR, Sir99, Dirdif 99.2 and Crunch for
auto-building of structures. The Squeeze option was discussed
for handling nasty solvent effects.
This resulted in a discussion on the ethics of using squeeze
modified data for publications. A summary from Sandy Blake was he did not see a problem as long
the submitting author(s) described honestly what
they did and why they did it. It was mentioned this option would
be best put inside structure refinement refinement software.
One thing missed from the formal demonstration, was the use
of Platon to do very quick and user-friendly
searching of the Cambridge database for cells and related structures
via spawning Quest in the background at the click of a button.
Lachlan Cranswick (CCP14 Secretary - Hurrah!)
talked about various freely
available software programs relevant for Chemical Crystallography with the emphasis on the
benefits of making use of the available genetic diversity of the available software.
This included running through the available indexing,
solving, refinement, structure quality checking, photorealistic rendoring, animation of
structures, and briefly on powder diffraction options.
Mention was made of the not yet released (enable "please be patient mode")
SXGRAPH in WinGX
(by Louis Farrugia - primarily for GUI control
of Shelx files) in the context of its ability to import/clean fragments then
pass it easily into Dirdif for fragment searching.
The latest Sir2000 was also mentioned with comments
on large structures it had already solved (structures with "202 non-H atoms" to "1,910
non-H atoms (with 374 waters))". The aim is for Sir2000 to handle greater than
2000 atoms in the asymmetric unit. (Not yet released - most likely after
ECM 2000 in Nancy - please be patient). Information on easy download, installation and running of the
Crunch
and Shake-n-Bake software was also explored. A live
demonstration of using the
Crysfire /
Chekcell combination for
indexing of powder data (when those single crystals are too small) was given. As well
as suggesting the Sirware EXPO
software as a first call for trying to solve structures from
powder data when a cell and spacegroup has been obtained. Concerns were
raised by George Sheldrick over Crystalographic suites that make it easy for users
to avoid seeing the warning messages. This was discussed by the audience.
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