Semi-classical methods for vibrational energy levels of triatomic molecules

Abstract

The method recently proposed by Chapman, Garrett and Miller for semi-classical eigenvalues of non-separable systems has been applied to the triatomics SO₂ and H₂O. The Hamiltonian is expressed in normal coordinates, using potentials V=V(Δr₁, Δr₂, Δθ). The energy levels are compared with corresponding quantum mechanical energy levels. For SO₂, the fundamental frequencies differ by at most 0.1 cm^–1, and for H₂O they differ by at most 1.6 cm^–1.