> I have a problem with the PowerPC version of RIETAN: The errors of the
> temperature factors are at least one magnitude larger than those obtained
> with GSAS or WYRIET. Has anyone observed this error and maybe fixed
> already?
E.s.d's of variable parameters calculated in the conventional way (probably, GSAS, WYRIET, and other Rietveld-refinement programs adopt this manner) are considerably underestimated and usually ca. two/three times larger than real standard deviations.
However, no satisfactory method of calculating e.s.d's has yet been devised. Scott's method is far from perfect but may give e.s.d's that are much nearer to real values. In the latest version of RIETAN, RIETAN-97beta (available from ftp://ftp.nirim.go.j
p/pub/sci/rietan_beta), we can select two different ways of calculating e.s.d.'s: conventional and Scott's methods. Anyway, you had better quote Scott's paper:
H. G. Scott, J. Appl. Crystallogr., 16 (1983) 159.
when using his method because those who read your paper may
misunderstand that parameters refined by you have too large
e.s.d's.
By the way, on this mailing list, I will soon inform the
availability of Fourier/D synthesis programs for the Macintosh,
fousynMAC and meviusMAC, which have been developed by Dr.
S. Kumazawa. Someone searched for such a kind of programs
before in this mailing list. Because the graphical part of
meviusMAC adopts PGPLOT and their source programs are distributed
by Dr. Kumazawa, it is very easy to transport them to any
computers including IMB-PCs. You can refer to its temporary
manual in part of my home page:
http://www.nirim.go.jp/~izumi/rietan/fourier/fourier.html.
I am also pleased to tell that the forthcoming version of
ATOMS (Ver. 4.0) by Shape Software has a new feature of
reading in *.xyz files created by RIETAN, which must be
a good news for users of RIETAN. I have been strongly
impressed by its three-dimensi
onal display and animation modes.
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Fujio IZUMI
National Institute for Research in Inorganic Materials
4th Research Group
1-1 Namiki, Tsukuba, Ibaraki 305, Japan
TEL: +81-298-51-3351
FAX: +81-298-52-7449
E-mail: izumi@nirim.go.jp
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