Applying diatomic in molecules in excited electronic state calculations for flexible polyatomic molecules. The I3 molecule

In this paper we calculate the 64 potential energy surfaces of the manifold of states of I3 that dissociate to three ground state iodine radicals as functions of bend and stretching coordinates. We describe the set of quantum rotations necessary to generate the full Hamiltonian matrix using only I2 experimental energies and describe the formal connection between this approach and the usual diatomic in molecules Hamiltonian formulation. The I3 excited state surfaces calculated in this way are used to compute various excited state features in the photoelectron spectrum of I3− and we use these results to interpret the recently measured spectrum.