[sdpd] Re: Is it just awfully quiet these days?

[L.M.D.Cranswick... @dl.ac.uk (L. Cranswick)]

On the quiet nature of crystallographic newsgroups lately - it could
take a few months for those who went to Glasgow to recover and
even get up to slightly normal levels of posting.

----

For indexing of the following - have you routinely used Le Bail 
fitting in conjunction with Crysfire/various powder indexing
programs to get a global whole profile view of how good the
cell is?  This is rather easy to do once you have set up at
template file (in Fullprof at least) when trial cells are 
produced by Crysfire based indexing programs:

Doing a fit with XFIT for Win95
   http://www.ccp14.ac.uk/tutorial/xfit-95/xfit.htm

Then Powder Indexing with Crysfire:
   http://www.ccp14.ac.uk/tutorial/crys/
TAUP (inside Crysfire) gave two interesting Orthorhomic cells
(one alluded to in the DOC file)  If you suspect Orthorhombic
or higher, TAUP will generally find something if there is
anything to be found.

Swapping quickly between Crysfire and a suitable Rietveld
program (e.g.:)
Le Bail fitting using Winplotr to view plots; Fullprof for DOS 
to do the Le Bail fitting and PFE text editor to cut/paste/
edit the Fullprof PCR files (all in separate Windows for
maximum ease)

Winplotr:
  ftp://bali.saclay.cea.fr/pub/divers/winplotr/
  http://www.ccp14.ac.uk/ccp/ccp14/ftp-mirror/fullprof/pub/divers/winplotr/
 
Fullprof for DOS:
  ftp://charybde.saclay.cea.fr/pub/divers/fullprof.98/ms-dos/
  http://www.ccp14.ac.uk/ccp/ccp14/ftp-mirror/fullprof/pub/divers/fullprof.98/ms-dos/
   
PFE Text Editor for Windows:
  http://www.lancs.ac.uk/people/cpaap/pfe/
  http://www.ccp14.ac.uk/ccp/web-mirrors/pfe/people/cpaap/pfe/index.html

---

A Le Bail whole profile fit gives a good graphical quality 
indication of the trial Cells.  You can also use the weighted
profile as a guide to the quality of the fit and possibly
working out the spacegroup when peaks are highly overlapping.

Example XFIT, Xfit ready Crysfire file and Fullprof files 
(with some screen dumps) at:
   http://www.ccp14.ac.uk/test/sdpd/

Could any of the low intensity reflections be possible
impurity peaks?

Lachlan.

PS:  You should be able to do similar very quick Le Bail fitting
in GSAS as well.  Setup and optimise one of the cells.  Then for
new trials, paste in the new Cell; do a powpref to regenerate
the HKLs, then genles.

> 
> Hi Everyone!
> 
> 	In the interest of stimulating some discussion and seeking some help
> let me lay out the problem I am working on.  I am a fourth year graduate
> student and this is the first crystal structure I have ever tried to solve.
>  The data was collected at NSLS beamline X7B under the guidance of Jon Hanson.
>  A 0.7 mm capillary of CuAlCl4 was exposed to C2H4 and a new crystalline phase
> formed.  Gravimetric analysis suggests an empircal formula of C4H8CuAlCl4 for
> this gas adduct phase  The gas sorption was observed by time resolved powder
> X-ray diffraction using a Translating Image Plate (TIP) detector built by P.
> Norby.  An image plate of the full Debye-Scherrer rings for the ethylene copper
> aluminum chloride adduct was analyzed using A. Hammersley's fit2d software.
>  The fit2d parameters used on the unknown structure yielded d-spacings within
> 0.01 A for a control plate, CuGaCl4 (whose structure had been determined by
> single crystal X-ray diffraction).  The output of the fit2d, in GSAS format
> (von Dreele and Larson), was peak picked with GPLFST (acknowledgement?) and
> then the CRYSFIRE (R. Shirley) interface to a suite of indexing software was
> used.  Only TREOR (P. E. Werner) and ITO (acknowledgment?) yielded possible
> unit cells (due to my not being familiar with the other routines, no doubt).
>  Further discussion of my search for the correct unit cell (as well as an
> edited peak list and screen formated gsas and instrumental data files of the
> diffractogram) can be ftp'd from
> 
> chjmpc3.chem.ncsu.edu.
> user:jobic
> password:jobic
> 
>   At this point I am using the cells in C. Giacovazzo's EXTRA routine to
> extract Fobs for hkl's.  I had trouble fitting the background in EXTRA so I did
> a background subtraction using an EXCEL spread sheet and a curve fitting
> program (CURVFIT).  I used the CONVERT (acknowledgment?)software convert ascii
> files into Reit7 format for EXTRA.   Some trial runs with SIRPOW have not yet
> produced any chemicaly reasonable value.
> 	I would like to try ESPOIR.  I have strong reasons to believe
> tetrahedral tetrachloroaluminate anions are one of the consituents of the
> structure and would like to enter them in as integral units, but do not know
> how to proceed.
> 	I wish to acknowledge the collaboration of Haiming Liu of Clare Grey's
> group at SUNY Stony Brook in this project.  Thank you all for your time in
> reviewing my work and I would like to thank all the contributers to sdpd, as
> well as the reitveld list, for discussions which have helped me get as far as I
> have working on this solution.
> 
> Roger
> 
> 
> Roger M. Sullivan
> Department of Chemistry
> Box 8204
> North Carolina State University
> Raleigh NC, 27965
> smsulliv... @pams.ncsu.edu


-- 
Lachlan M. D. Cranswick

Collaborative Computational Project No 14 (CCP14)
    for Single Crystal and Powder Diffraction
Daresbury Laboratory, Warrington, WA4 4AD U.K
Tel: +44-1925-603703  Fax: +44-1925-603124
E-mail: l.cranswick... @dl.ac.uk  Ext: 3703  Room C14
                           http://www.ccp14.ac.uk