[EMAIL PROTECTED] wrote:
Dear all,
I'm trying to fix the limits of one lattice parameter in Fullprof. So I put
Nre=1 and limited the parameter between 5.49 and 5.50, but at the end of the
refinement its value results about 0.43; a similar result is obtained also when
I try to limit the other cell edges.
for completeness, when I try to limit other parameters, such as Biso everything
works OK.
Can somebody suggest me how to overcome this problem?
Thanks in advance, Alberto
The cell parameters are not refined directly in FullProf! The box
limits constraints (Nre /= 0) do not apply to cell constants but to the
coefficients of the quadratic form: 1/d^2 = A h^2 + B k^2+C l^2 + D kl
+ E hl + F hk. So, if you want to make some box constraints to the cell
parameters you must calculate the corresponding limits to A,B,C,E,E,F.
In your case (I suppose it is an orthorhombic system in order to avoid
mixing of several cell parameters in the coefficients A,B,...), for
instance, if b should be constrained to be between 5.49 and 5.50, then
B=1/b^2 should be constrained to be between 0.03305785 and 0.03317839.
Normaly you do not need to apply this kind of constraints to cell
parameters because they are stable.
Regards,
Juan Rodriguez-Carvajal
