The electronic states of TeO₂

The electronic properties and geometry of TeO₂ have been calculated using an ab initio complete active space, multi-configuration self-consistent field method with a double-zeta plus polarization Gaussian basis set. Compact effective potentials, derived from relativistic atomic orbitals for the tellurium atom, were used to replace the atomic core electrons. Like ozone, the ¹A₁ ground state is found to have a double minimum consisting of a lower-energy open form and a higher-energy ring geometry with an OO bond. The calculated ground-state equilibrium bond length (R=1.83 Å) and angle (θ=111.9°) agree well with experiment. The ring structure (R=2.02 Å and θ=63.6°) is calculated to lie 2.02 eV above the ground-state equilibrium geometry with a 3.13 eV barrier for open → ring. The first excited state, ³B₁, is predicted to be bound relative to the ground-state dissociation energy.