The Jahn–Teller and pseudo‐Jahn–Teller effects in the anion photoelectron spectroscopy of B 3 cluster

The photodetachment spectroscopy of B   3 −anion is theoretically studied with the aid of a quantum dynamical approach. The theoretical results are compared with the available experimental photoelectron spectra of B   3 − . Both B   3 −and B 3 possess D 3 h symmetry at the equilibrium configuration of their electronic ground state. Distortion of B 3 along its degenerate vibrational mode ν 2 splits the degeneracy of its excited $\widetilde{C}^2E^{\prime}$ electronic manifold and exhibits ( E ⊗ e )‐Jahn–Teller (JT) activity. The components of the JT split potential energy surface form conical intersections, and they can also undergo pseudo‐Jahn–Teller (PJT) crossings with the $\widetilde{X}^2A_1^{\prime}$ electronic ground state of B 3 via the degenerate ν 2 vibrational mode. The impact of the JT and PJT interactions on the nuclear dynamics of B 3 in its $\widetilde{X}^2A_1^{\prime}-\widetilde{C}^2E^{\prime}$ electronic states is examined here by establishing a diabatic model Hamiltonian. The parameters of the electronic part of this Hamiltonian are calculated by performing electronic structure calculations and the nuclear dynamics on it is simulated by solving quantum eigenvalue equation. The theoretical results are in good accord with the experimental data. © 2006 Wiley Periodicals, Inc. J Comput Chem 27: 1093–1100, 2006