There are many manuscripts are available on the calculation of tolerance factor (t) and Octahedral factor of perovskite materials. But every articles predicted different value and it is not matches with formula of t after calculation. So for me its very confusing regarding calculation of t and u value to CH3NH3PbX3 (X= I, Br, Cl) perovskites.
On another difficulty about putting the value of X also. In perovskite there is 3 molecule of X but I think in calculation used only one molecule value. In some calculation value of atomic radii of Methylammonium is given 217 pm and in some cases 2.38 pm. So it is very difficult to calculate accurate value for CH3NH3PbI3, CH3NH3PbBr3 etc. Please suggest me proper calculation in details. I am also attaching some articles about confusing calculations.