Dear Rory
Careful about confusing 2theta zero offset and hight. They are highly
correlated, but they are not the same. Hight is angular dependent, the other
is not. This will cause problems when one has a wide 2theta range to refine.
Most Rietveld programs can deal with the two independantly but I wouldn't let
them refine at the same time.
Martin
M Vickers
Dept of Crystallography
Birkbeck College
Malet St
London WC1E 7HX