A Global Algebraic Treatment for XY2 Molecules : Application to D2S

Abstract

We suggest to use for XY 2 molecules some results previously established in a series of articles for vibrational modes and electronic states with an E symmetry type. We first summarize the formalism for the standard u(2) ⊃ su(2) ⊃ so(2) chain which, for its most part, can be kept for the study of both stretching and bending modes of XY 2 molecules. Next the also standard chain u(3) ⊃ u(2) ⊃ su(2) ⊃ so(2) which is necessary, within the considered approach, is introduced for the stretching modes. All operators acting within the irreducible representation (irrep) [N 00] ≡ [N 0] of u(3) are built and their matrix elements computed within the standard basis. All stretch-bend interaction operators taking into account the polyad structure associated with a resonance ω 1 ≈ ω 3 ≈ 2 ω 2 are obtained. As an illustration, an application to the D 2 S molecular system is considered, especially the symmetrization in C 2v . It is shown that our unitary formalism allows to reproduce in an extremely satisfactory way all the experimental data up to the dissociation limit.