I use expgui, and fullprof suite

EXPGUI and Fullprof is good option. In this case, the A (lattice parameter) can be measurement (by Rietveld Refinement or Bragg's Law) and compared with the bond lengths for the molecule. You see in http://www.ccp14.ac.uk/

use expgui, and fullprof suite this is good option

I wish to recommend single crystal XRD after developing a pure single crystal of your compound.