Generating LARGE Cartesian Lattices?

Uncle Al UncleAl0 at hate.spam.net
Wed Oct 16 16:04:38 EST 2002


Saco wrote:
> 
> Have you checked Mercury?
> http://www.ccdc.cam.ac.uk/prods/mercury/index.html
> It can read .cif and save as .mol, but I'm not sure that's what you
> are looking for.

My needs as stated are very specific.  Given the crystal strucure of
elemental tellurium, ICSD 65692.CIF (fractional coordinates), generate
an (unordered) *.XYZ list of Cartesian coordinates for a given radius
(or number of unit cells in each direction x,y,z).  Almost any crystal
software package will do this, ORTEP to ATOMS.  

The *problem* is that I need a 120-150 A radius, or about 250,000
atoms (about 9 MB of output).  Loathsome fat, stupid, and incapable
Windows freezes solid at those memory requirements if any attempt is
made to order the list or output in a window instead of a scratch
file.  I have exhausted obscenities in seven languages damning
BillGates to Hell

Mercury is a very capable, very sophisticated package.  I'll give it a
run.  I suspect I need a very primitive, very incapable program that
just builds a lattice to a given radius.  I'm looking at crystallff. 
It could be the perfect tool!  Its extensive documentation very neatly
omits giving even a single example of an input sequence.  I'm down to
one fatal error.
 
> The following link gives high-pressure Te structure.
> http://cst-www.nrl.navy.mil/lattice/struk/Te.html

"8^>)  I specifically need the helical P3(1)21/P3(2)21 hexagonal
structure.
 
> BTW, there has been recently a new solution proposed for the
> crystallographic phase problem.
> http://xxx.lanl.gov/abs/cond-mat/0209690

Isn't that something?  It will be interesting to see if it is adopted
as a general method.

Thanks for the help.

-- 
Uncle Al
http://www.mazepath.com/uncleal/
 (Toxic URL! Unsafe for children and most mammals)
"Quis custodiet ipsos custodes?"  The Net!





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