Hi Usama,

There are a lot of factors that can influence this mismatch between observed and calculated peaks, from preferential orientation of your crystallites to structure of your sample that could be different by the one that you're trying to model.

I would suggest you to collect data counting for a longer time. Also trying to improve the resolution (changing the slits of your diffractometer) could help you to elucidate if you have phases with similar cells coexisting or even if you have a change in the crystal system (e.g. from orthorhombic to monoclinic).

You can also use "free format" for the experimental data. examples: https://www.ill.eu/sites/fullprof/php/tutorials.html

I hope this helps. Goodluck!

Thanks for the answer Galib. Recollection of data is not possible at present time. And yes the spacegroup could be something other than the one im using. But for now this is the best matching spacegroup I have. I would like to know if there is anything Im overlooking that could help me fit the data without changing the entire spacegroup !

Actually, the fit you show in your picture is quite good.  Given inherent noise and other issues such as particle size of actual material, I honestly doubt you would get  a better fit.  

Thanks for the answer Dr. Merola. I usually see much lower chi^2 values (around or less than 2) reported in publications. Although, admittedly, the difference plot in those publications do not look that much better to my beginner eyes. Do you think my obtained fitting is acceptable for publication purposes?