New regularities in vibrational spectra

The frequencies of about 150 diatomic molecules are expressed as functions of the equilibrium distance and of the numbers of electrons in the outer shells of both atoms. The frequencies are calculated for homopolar molecules with single bonds, with multiple bonds and for molecules with strong polarity. The contributions of s- and p-electrons to the force constant are practically equal, and the same parameters are valid for all periods of the periodic system. The theoretical implications are discussed.