The far-infrared spectra of A-type zeolite samples show broad bands sensitive to cationic exchange. We present the far-infrared spectra of five A zeolites with Li+, Na+, K+, or Ca2+ cations. The vibrational frequencies of the exchangeable cations with respect to the anionic framework have been calculated, taking in account the ions of eight sodalite units. In the potential interaction between cation and framework (electrostatic, polarization, dispersion, and repulsion), the repulsion constants are determined by a combination method, and the effective ionic charges by the orbital electronegativity method.