An algebraic Hamiltonian for electronic and nuclear degrees of freedom based on the vector model

An approach which considers both nuclear and electronic motions for molecular systems is derived using algebraic techniques within the vector model. The dynamical symmetries of the Hamiltonian thus derived are examined and shown to account for the analytic diagonalizability of the LEPS level potential function for molecular systems. The initial application is to the H₃ collision system, demonstrating the ability of the model to treat systems without bound states. Extensions to more complicated systems are also considered, and these efforts allow for the determination of the algebraic source of the coupling in the “diatomics in molecules” (DIM) potential surface. In general, these terms in the DIM approach preclude analytical diagonalization of the Hamiltonian, which may also be understood in terms of the dynamic symmetry of the corresponding algebraic description.