Dear GSAS users, first of all Good Easter to everybody (even if quite late!).
I have a problem with GSAS: I don't understand why, during a refinement of a TOF neutron profile, I see a big increase of the Bragg index RF^2 (from 12% to 61% !!) if I insert in the refinement just three little peaks (i.e. if I start my histogram from 0.67 instead from 0.7 Angstrom). Profile indexes Rp and wRp remains the same, as these 3 peaks are well fitted by the tetragonal symmetry chosen !! So they don't belong to an impurity, and space group seems right! I don't have many peaks, so I would like to use also these peaks in the refinement. Another little question: which convergence criterion do you think it's better for a normal Rietveld refinement? In Expgui the default value is fixed to 0.01, but I read it could be bigger but less than 0.10. Thanks a lot in advance, marco -- Marco Sommariva Department of Materials Science University of Milano - Bicocca Via R. Cozzi 53 - 20125 MILAN, ITALY Phone +39.02.6448.5141 (5142) Fax +39.02.6448.5400 e-mail: [EMAIL PROTECTED]
