newbie in Refinement

[Riza Iskandar]

Dear colleages,   I had downloaded the EXP-GUI software several days ago, and right now I’m trying to understand that software. Using example raw file from GSAS example file, I try to run the Nickel TOF file.  Could anyone help me to answer these questions?   1. Does anyone have done this problem? (run the nickel example)  what is the minimum chi (convergence) can be achieved?   2. Does it need profile refinement? 3. What is the minimum value of chi for every refinement process? I meant what is the minimum value that we can declare that our refinement process is successful? 4. I also did some refinement using APD (Philips Diffractometer) with the same sample as I did by GSAS, but it shows different refinement result, especially in chi value. I am using Pure Fe powder and X-ray diffraction using Co tube. Can anyone explain to me why it is happen?     Thank you for your advanced     Riza Iskandar Jl. Cinere Raya No 31 Depok, Jawa Barat 16514 Indonesia