Subject: Summary of Space Groups

From: Jan Gryko <[email-masked]>
Date: Tue, 13 Jun 95 19:14:00 M

[[ SUMM.TXT : 4665 in SUMM.TXT ]]

       Summary of SPACE GROUPS  or How get atom coordinates
       in the unit cell from crystallographic data
       
----------------------------------------------

  From: [email-masked]

        The crystal builder module in Cerius does what you want.
                        Bob
----------------------------------------------
  From: [email-masked]

  Cele Abad and TJ ODonnell have written such a program, TABLES, that also
  will display several repeats of the crystals...not display, calculate the
  coordinates of.

  If you want more information contact:

[email-masked]
[email-masked]

If these fail:

[email-masked]
cele.abadzapatero.abbott.com
[email-masked]

The second cele address should be
[email-masked]

  @@@@@@@@@@@      Yvonne Martin, Senior Project Leader
             @     Computer Assisted Molecular Design Project
   @@@@@@@@  @     D-47E, AP10 2fl
  @          @     Abbott Laboratories
  @          @     100 Abbott Park Road
   @@@@@@@@@@      Abbott Park, IL 60064-3500
                   Phone: 708 937-5362 FAX: 708 937-2625

-----------------------------------------------------------
From: "Leslie Glasser" <[email-masked]>

The program Space Groups for Windows provides generated atom 
coordinates from an asymmetric unit.
It is available from Atomic Softek, 604-201 Jackson St W.,
Hamilton, Ont., Canada, L8P 1M2
Tel 905-528-4506  FAX: 905-528-9084

Leslie ==============================================================
(Prof.) Leslie Glasser                     Dept. of Chemistry    
E-mail: [email-masked]      Univ. of Witwatersrand     
Tel: Intl + 27 11 716-2070                 P. O. WITS 2050            
Fax: Intl + 27 11 339-7967                 South Africa               
Home Pages:  University      http://sunsite.wits.ac.za
             Chemistry       http://www.chem.wits.ac.za

-----------------------------------------------------------
From: cbas25 <[email-masked]>

The program INTERCHEM  which is available from QCPE includes an option to
derive all the atom coordinates for a unit cell (or nests of unit 
cells).  The program allows you to display the results in the usual 3D on 
SGI machines.  If you just want the method for doing it then it would be 
possible to abstract the relevant portions from the source code.  There 
are two implimentations of the method in the program, which take as input 
either the coordinates in the form of the Cambridge Crystallographic 
Database "XR" file or the CCD "FDAT" file.  In the former case the 
program uses built-in data on the spacegroups.  The "FDAT" file actually 
includes the data for the replicating matrices itself.  This tends to be 
more reliable, since sometimes there is ambiguity in matching up the data 
in the "XR" files with published tables.  

Incidentally, it was only when I came to program this stuff that I became 
aware of the fact that the most symmetrical space groups involve the most 
problems.  To get a nest of 3 x 3 x 3 (i.e.27) unit cells of the sodium 
chloride crystal requires the generation of many thousands of atom 
positions, and then the elimination of the identities.  There are 
probably easier ways of doing this, but not being a crystallographer, I 
tended to use a "brute force" method.
Yours sincerely
Peter Bladon

-----------------------------------------------------------
From: "[email-masked]" <[email-masked]>

        The Crystal Builder of our product, Space Groups for Windows, will 
answer the question you posted through CCL.  Space Groups for Windows also 
have other capabilities, such as to show the position and symmetry 
distributions of all the space groups by both tables and 3-D graphics.  The 
program is designed for scientists and educators to obtain the information 
of space groups and quickly build crystals.  If you would like to have more 
information about our product, please contact me. 

Anne J. Tao

------------------------------------------------------------------------------
Return-Path: <[email-masked]>

  I have the old Oak Ridge crystallographic programs in Fortran
called ORFEE and ORTEP.  Both do much more than you want, but have
these functions built in.  One just inputs the xyz coordinates from the
crystal paper, and the unit cell parameters.  Then from the International
Tables one selects the tranformation information.  The program
generates the transformed coordinates.
  I own several commercial programs that cost a great deal of money
but are big dissappointments.  The have the transformation information
built in, but don't allow any modifications.  Therefore one gets a
fancy picture of the molecule, but so what.  Suppose one wants to
add molecules that are not in the unit cell.  Sometimes hydrogen
bonding is to neighbors not in  the unit cell.  What I like about the
Oak Ridge programs is that this dooesn't matter.  One can just invent
new unit cell transformations.
  Regards, Dave Close.