Abstract
The potential energy surfaces (PES) of the Jahn–Teller distorted doublet 12E0 (1B2/1A1) ground state and 12E00 (2B1/1A2) excited state of alkali metal trimers (K3,Rb3) are studied with three high-level computational chemistry methods whose results are compared: single-reference coupled cluster, equation-ofmotion coupled cluster and multi-reference second-order Rayleigh–Schrödinger perturbation theory. The doubly degenerate E electronic state interacts with the twofold degenerate vibrational e mode.
We use the Ee Jahn–Teller effect theory to analyze in detail one- and two-dimensional cuts of the PES as a function of the symmetry-adapted internal coordinates Qs, Qx and Qy and we extract the associated Jahn–Teller parameters. Spin-orbit coupling is accounted for by means of the Effective-Core-Potential-LS technique and spin-orbit splitting constants are extracted.
We also provide the geometries, the binding energies and tentative vibronic spectra for the 12E00 12E0 transitions.