chem cryst
X-ray Crystallography
University of Oxford
chem cryst news
Many small changes in Regularise Replace thanks to a CRYSTALS workshop in Toulouse organised by Carine Duhayon and Laure Vendier. Cif generator now properly includes esds on refined hydrogen bonds, has incrreased figure-fields for cell parameters, and appends constraint and restraint information as _iucr_ data items at end of cif. Improved scaling of difference Pattersons - see forthcoming paper by Flack, Sadki, Thompson etc. Absolute configuration routine (based on PLATON with Ton's permission) extended to provide more diagnostics and additional data to be re-input as absolute-structure strengthening restraints (see paper by Howard etc above). Error tracking for "USE" files has been improved.
Collaboration with Ernesto Mesto (Dipartimento Geomineralogico - Università degli Studi di Bari) uncovered over-sights in the original 1979 code, which lost contributions when a twin component fell onto a centring absence. Difference maps with twinned data now seem to reveal hydrogen atoms very reliably.
Bob Carruthers worked with John Rollett and Keith Prout to produce the core data management and crystallographic subroutines upon which CRYSTALS is built. It was his vision and meticulous attention to detail which provided a kernel which still works well after 40 years of change in computing technology.
University of Oxford Chemical Crystallography Laboratory
The Chemical Crystallography Laboratory is located in the basement of the new Chemistry Research Lab on the corner of South Parks Road and Mansfield Road. The laboratory contains state of the art crystallographic diffraction equipment, laboratory space for sample preparation, office space for computational and theoretical work.
The Structure Analysis Service is run by Amber Thompson, who
has recently joined us from Judith Howards lab in Durham.
Members of other groups within Chemistry
are encouraged to do their own
structural analyses, and space, computers and patient tuition
are available for them in the laboratory.
David Watkin's group
currently consists of Mustapha Sadki (systems programmer), N. Dave
Brown (DPhil), Professor Terry Willis (emeritus) and Kirsten
Christensen (academic visitor from Diamond).
The Chemical Crystallography Laboratory has a long history of involvement
in software development. Our software, CRYSTALS
(for single crystal X-ray structure refinement and analysis)
is used world wide.
Oxford University has agreed that the code and exectutables of CRYSTALS
can be made Open Source once appropriate
copyright
messages have been included in all the files.
This applies to both educational and commercial uses.
The internal data-structure of CRYSTALS has now (after 30 years)
reached its limits, so that major developments to the program have
become increasingly difficult.
Minor enhancements and bug-fixes continue to be made,
so that the program could be maintained into the next decade.
Making CRYSTALS Open-Source has greatly improved the possibility
that the internal data structures will be replaced while preserving
or enhancing the crystallographic features.
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