This monograph deals with ab initio variational calculations of vibrational-rotational spectra of bent triatomic molecu- les. It gives a comprehensive derivation of the Eckart-Wat- son Hamiltonian in terms of a "f" coordinate system. The de- rived Hamiltonian is in the most general formand so is shown to collapse to C2v and D3h rectilinear Hamiltonians. Concommitant with the derived Hamiltonians, a complete solu- tion algorithm of the nuclear Schr-dinger equation is detai- led. The eigenfunctions of numerical finite-element soluti- ons of three one-dimensional Schr-dinger equations are spli-...