BOSON-REALIZATION MODEL FOR THE VIBRATIONAL-SPECTRA OF TETRAHEDRAL MOLECULES - COMMENT

An algebraic model in terms of a local harmonic boson realization was recently proposed to study molecular vibrational spectra [Zhong-Qi Ma et al., Phys. Rev. A 53, 2173 (1996)]. Because of the local nature of the bosons the model has to deal with spurious degrees of freedom, An approach to eliminate the latter from both the Hamiltonian and the bas is was suggested. We show that this procedure does not remove all spur ious components from the Hamiltonian and leads to a restricted set of interactions. We then propose a scheme in which the physical Hamiltoni an can be systematically constructed up to any order without the need of imposing conditions on its matrix elements. In addition, we show th at this scheme corresponds to the harmonic limit of a symmetry-adapted algebraic approach based on u(2) algebras. [S1050-2947(97)03811-0].