I don't really understand the problem. Since the checkbox are not checked, the parameters are supposed to be fixed. 

I have an additional question : usually, the occupation is defined as multiplicity of the site/multiplicity of a general position and is then < 1. How did you calculate your ones in the pcr file ?

Dear William,

You may contact my friend vishwajit gaikwad of Nagpur university and give my reference (Punith Kumar V.,MIT Mysore). He is expert in the field of BiFeO3 and he'll definitely help you.

Your question is not clear. Do you want to know the atomic positions of BiFeO3? Otherwise they are already fixed in your input file! And the occupancy factors are wrong.

Dear Christophe Lefevre & Marcella Bini I dont understand the value of X,Y & Z asked to enter in fulproff software for XRD refinement. Since a,b and c values are cell parameters that we get in our JCPDS. My question is what is X,Y and Z to be enter in fulproof software?

Hi Punith, 

Thank you, I make contact Mr. Vishwajit for BiFeO3 refinement. 

Dear William R.V.

X,Y and Z are the fractional atomic coordinates. Taking those from J. Phys. Chem. Solids 32 (1971) 1315, you have to input the following values in the pcr file (the last column is the occupancy factor)

Bi 0.000 0.000 0.000 0.3333

Fe 0.000 0.000 0.2212 0.3333

O 0.443 0.012 0.9543 1.000

Best wishes,

Dear Christophe Lefevre,

Thank You very much for your information, it's far more useful for my work..