where, 𝑟 #-.. = 𝑟 5677 + 𝑟 89: , with 𝑟 5677 being the distance between the centre of mass of the molecule and the atom with the largest distance to the centre of mass (excluding hydrogen atoms), and 𝑟 89: is the corresponding ionic radius of this atom. Cheetham et al found, using their adjusted relationship, that although cubic perovskites were still typically found in the region 0.9-1.0, values of 0.8-0.9 led to distorted perovskite structures, and those less than 0.8 generally led to other architectures such as ilmenite. On the other hand, values larger than 1.0 were observed to yield many hexagonal structures.