Diffractometer and plotting programs

Shaw Mr. G shaw at ccu1.aukuni.ac.nz
Mon Oct 18 18:03:26 EST 1993

                  ************** Help ******************

I'm the Crystallography Technician at the Auckland University Dept
of Chemistry and my job is to run the Enraff Nonius CAD4
Diffractometer and process the data from it to give structures.

1) Are there any other CAD4 users out there and do you have the same
problems we have ie. "data overrun" messages appearing on the
terminal, oscillations of the axes, mysterious loss of orientation
controls and orientation matrix inversion etc etc. I think the
problems are unrelated but I could be wrong. The cost of bringing in
an Enraff engineer is beyond our means so any help would be very

2) As part of the CAD4 we also use an Enraff Nonius LN2 cryogenic
crystal cooler. I have only recently managed to get it working
properly as it was supplied  with a faulty seal in the evaporation
dewar. We still have problems with leaky  valves in the transfer
dewars. Does anyone know of suppliers of low pressure cryogenic
valves for less than $400 NZ each ?

3) We currently use a program called ORTEP (size 153,575 bytes, date
stamped 1987) for producing a publication  quality diagram showing
molecules with anisotropic thermal ellipsoids. The version we have
runs on a PC and is basically a slightly modified version of the
original code written in 1965 and could probably win an award as the
worlds most un-user friendly piece of software ever written in the
history of computing. Below is part of a typical input command

,301,8,11,24,1.0 ,401,155501,-3855501
2,511 2,1,1,5,16,4,1.7,2.2,0.04
1,701 ,,,,1,26
2,812 2,1,1,5,16,4,1.7,2.2,0.04

  Each line represents a command followed by a series of variables
and it probably comes as no surprise, that to plot even a small
molecule in the desired orientation typically takes two hours of
blood sweat and tears. So my question is, does anyone have an
improved version of ORTEP for the PC or better still a different
plotting program (that gives anisotropic thermal ellipsoids) that
can produce HPGL or Postscript files.

4)  We also use a plotting program called PLUTO (size 197,007 bytes,
date stamped 1987) for doing student crystallography projects. PLUTO
is easy to use but can only show atoms as spheres and all the plots
on paper are mirror images of what appears on the screen ! Does
anyone have an improved version of PLUTO ? 


        Mike Buckler


Mike Buckler,
4th Floor Diffractometer Technician,
Dept of Chemistry,
University of Auckland,
Symonds Street, 
New Zealand.


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