Traditionally, why Rwp reported in percentage?

iangie

One of my fitting report given by Topas output file is:
r_exp 1.259 .......... r_wp 4.378 ............ gof 3.478

But some literature (especially those more than 10 years older) report Rwp in several to tens percent.

May I ask why are they different? Is there any anternative difinition of Rwp other than what is stated in Topas Technical Reference?

Thank you. :)

ahhill

It could all be dependent on whether a background is taken into account.

See Powder Diffraction 21, 67-70, (2006) for a good bedtime reading.

Conveniently linked by Brian Toby on the following link.

http://x-ray.ucsd.edu/mediawiki/images/6/61/Toby_Rfactors.pdf

Adrian

iangie

Thank you Adrian, this paper reiterated all kinds of R definitions. Percentages were also used in this paper like "Rwp=23%", "Rwp=3.5%".

Actually, my question is, in my case shown above, should I report Rwp = 4.378 or 4.378% or 437.8%?

Thanks.

rowlesmr

Just reproduce the equation you use to calc your R factors and use the values that come out of that.

Covers all bases.