Molecular spectra from rotationally invariant Hamiltonians based on the quantum algebra suq(2) and irreducible tensor operators under suq(2)

The rotational invariance under the usual physical angular momentum of the suq(2) Hamiltonian for the description of rotational molecular spectra is explicitly proved and a connection of this Hamiltonian to the formalism of Amal'sky is provided. In addition, a new Hamiltonian for rotational spectra is introduced, based on the construction of irreducible tensor operators (ITOs) under suq(2) and use of q-deformed tensor products and q-deformed Clebsch–Gordan coefficients. The rotational invariance of this suq(2) ITO Hamiltonian under the usual physical angular momentum is explicitly proved and a simple closed expression for its energy spectrum (the “hyperbolic tangent formula”) is introduced. Numerical tests against an experimental rotational band of the HF molecule are provided. © 2003 Wiley Periodicals, Inc. Int J Quantum Chem 95: 1–20, 2003