Limitations of a Theoretical Method to Calculate the Rovibrational Spectrum of Trimers: H⁺₃

A method proposed to assign the symmetry character of the rovibrational spectrum of trimers has been applied to the case of H⁺₃. This system, much lighter than previously investigated rare gas three body molecules such as Ar₃ or Ne₃, constitutes a challenging example to test the possible limitations of this approach. Calculation of the corresponding rovibrational spectra for J=1 and rotational constants and the corresponding comparison with results from hyperspherical coordinates methods reveals that distortion Coriolis coupling terms, not accounted for in the original method, play a significant role for some specific symmetry representations. (author)