Relations for the coefficients in theI(I+1) expansion for rotational spectra

All the data now available for the ground rotational bands of actinide even-even nuclei and of rare-earth even-even nuclei (with bandcrossing angular momentum $I_c$≥16) are analyzed with the four-parameter I(I+1) expansion. The parameters obtained by the least-squares fitting definitely deviate from the relations derived from the Harris two-parameter ${\omega }^2$ expansion, but are closer to the relations deduced from the closed two-parameter expression by Wu and Zeng.