chi-squared Rietveld, Pawley refinement Reflex

Dear all,

I am working with reflex for XRD refinement (On material studio 6.1) and I am obtaining quite good CMACS values (I think) in the order of 1 to 2 %, however the Rp and Rwp factors are quite large in the order of 15-20 %. Does somebody know how I can obtain the chi-squared of the refinement? and, How good should be the CMACS values in a refinement?.

The CMACS parameter is poorly described in the help of the program.


Thanks a lot for your help