Ancient Greek temple three steps, the "crepidoma". The uppermost level of the "crepidoma" provides the surface on which the columns and walls are placed; it is called stylobate. Placed on the stylobate are the vertical column shafts, tapering towards the top. They are normally made of several separately cut column drums. Depending on the architectural order, a different number of flutings are cut into the column shaft: Doric columns have 18 to 20 flutings, Ionic and Corinthian ones normally have 24. Early Ionic columns had up to 48 flutings. While Doric columns stand directly on the stylobate, Ionic and Corinthian ones possess a
Ionic radius radii. The relation between soft-sphere ionic radii, formula_2 and formula_3, and formula_1, is given by formula_5, where formula_6 is an exponent that varies with the type of crystal structure. In the hard-sphere model, formula_6 would be 1, giving formula_8. In the soft-sphere model, formula_6 has a value between 1 and 2. For example, for crystals of group 1 halides with the sodium chloride structure, a value of 1.6667 gives good agreement with experiment. Some soft-sphere ionic radii are in the table. These radii are larger than the crystal radii given above (Li, 90 pm; Cl, 167 pm). Inter-ionic separations calculated