Subject: Making a crystal packing model in a computer

From: Hiroshi Ogura <[email-masked]>
Date: Sun, 10 Mar 1996 18:33:08 -0700 (MST)

Dear fellow list members,

I am in a process of making a computer-based model of crystal structures
for instructional purposes.  I want to input the atom coordinates of an
extended lattice, and then convert the input file into a .pdb file using
Babel.  Then, I would like to have the students use an interactive viewer
(e.g. Rasmol 2.5) so that they could rotate and manipulate the structure
as though it were a physical model. 

Obviously, making such computer-based model is going to be a formidable 
task.  I have a few points for with I seek your advice.

(1)  Calculating and inputting all the atomic coordinates is a tedious 
task.  I would much rather input the coordinates of a _unit cell_ and 
lattice dimension into a program or a macro, and have it generate all the 
coordinates.  Is there such a program?  Does a commercial software such 
as Spartan or Macromodel have a macro that I could use?

(2)  We also want to make models of unit cells that can be shown by 
RasMol.  Can RasMol handle 1/2, 1/4, and 1/8 atoms that are often found 
in a unit cell?  If not, is there a browser than can handle these types 
of atoms?

(3)  We would rather not use VRML which is coming into vogue right now, 
since it requires not only a helper application for a browser, but also a 
special application on the server side.  It might however become 
necessary for us to use VRML.  In that case, is there a free or cheap 
server application for a UNIX machine?

Thanks in advance!

--
Hiroshi Ogura            |  Take the sun from my heart,
[email-masked]    |  Let me learn to despise.
Dept. Chem, Univ. Ariz.  |  I'll show you another 
Tucson, AZ 85721         |  Who cannot tell lies.  --Richard Thompson