The crystal structure of a hypothetical compound A2B (A is the cation and B, anion) can be simply visualized as an FCC lattice with all the tetrahedral sites occupied. If two ‘E’ anions are substituted into the original lattice, what is the distortion(oversize or undersize) and changes to the original formula?My answer would be A8B2D2. Is this correct? how do I calculate distortion?