The Rietveld method broadens
continuously its application domain, but, up to now, the microstructure
approach remains highly disputable.
Improving the accuracy
of structure parameters is yet a sufficient target and justifies empirical
parameters having more recognized physical meaning is now desirable.
For anisotropic effects,
ellipsoids are progressively replaced by more general descriptions, in
terms of spherical harmonics and distributions of cell parameters, allowing
more complex cases to be accounted for.
Unfortunately, the user's
dream, which is to solve easily any problem through a friendly Graphical
User Interface, is far from being realized.
The problem (or possibly multiple problems) needs first to be identified. And the best adapted method has to be selected then, among an increasing (and confusing) number of possibilities.
The task is certainly not easy.
Anyway, best wishes !