We develop a model with
Hq(4) and
SUq(2) quantum group symmetries to describe the vibrational and rotational spectra of diatomic molecules. The representations of
Hq(4) and
SUq(2) and solutions to the quantum systems of q oscillators and q rotators are provided. We emphasize that the energy spectra of the q oscillator and q rotator exhibit remarkably the properties of the infrared, vibrational, and rotational Raman spectra as well as vibrational and rotational structures of electronic transitions of the diatomic molecule. When the parameters are properly selected, the spectra of this model coincide with the observed spectra of diatomic molecules. It is suggested that
Hq(4) \ensuremath{\bigotimes}
SUq(2) is an essential symmetry of vibrations and rotations in diatomic molecules.
We suggest the quantum Heisenberg group
Hq(J)(4) as the dynamical symmetry group of a diatomic-molecule system. The deformation parameter q of the
Hq(J)(4) symmetry group is a function of J (the quantum number of the angular momentum of the rigid rotation) and characterizes the interaction between vibration and rotation. The vibrational and rotational structures of diatomic molecules are compactly expressed using the quantum-group-theoretic approach. Taylor expansions of the analytic formulas from this approach reproduce the results of the anharmonic-oscillator and the nonrigid-rotator models. For some randomly selected molecules in particular states, the parameters are computed to fit the phenomenological formulas to high accuracy.