HI all
Looking at the Pair Distribution Function and refinement I come away with the following: Fitting in real space (directly to G(r)) should be equivalent to fitting to reciprocal space except for a difference in the cost function. Is this difference beneficial in any way. In other words does the radius of convergence increase or decrease. The computational effort required to generate G(r) is proportional to N^2 where N is the number of atoms within the unit cell. The computational effort for generating F^2 scales by N.Nhkl where Nhkl is the number of observed reflections. Is there a speed benefit in generating G(r) - my guess is that it's about the same. Note, generating G(r) by first calculating F and then performing a Fourier transform is not considered. In generating the observed PDF there's an attempt to remove instrumental and background effects. In reciprocal space these unwanted effects are implicitly considered. This seems a plus for the F^2 refinement. >From my simple understanding of the process, there seems to be good qualitative information in a G(r) pattern but can someone help in explaining the benefit of actually refining directly to G(r). Cheers Alan
