modified the Wiles Young Rietveld code to handle modulated structures. We
also modified the NBS*LSQ lattice parameter code to refine the modulation
vectors. Both codes are available by anonymous FTP from XRAY.ALFRED.EDU
2. S. A. Howard and R. L. Snyder, ``The Use of Direct Convolution
Products in Profile and Pattern Fitting Algorithms I. Development of
the Algorithms,'' {\it J. Appl. Crystallogr.} {\bf22}, 238-243 (1989).
(also see: \item R. L. Snyder, ``Analytical Profile Fitting of X-ray Powder
Diffraction Profiles in Rietveld Analysis,'' Chap 7, p. 111-131,
\underline{The Rietveld Method} Oxford University Press (1993))
developed a general profile fitting code called SHADOW, which will exactly
fit most profiles no matter how assymetric, the profile. It permits
deconvolution of the specimen profile function S from the profile function
and models S with size and strain broadening. It does not have an explicit
stacking fault model in its current form. The public domain version is
also available from the same FTP.
Bob Snyder