Molecular rotations in vibronically coupled systems

Abstract

A new general method to compute rovibronic energy levels and eigenstates in molecules with possibly strong vibronic coupling is presented. The method can be applied to arbitrary coupling mechanisms of electronic potential energy surfaces and is not limited to a special type of molecule. Explicit criteria for the applicability of the method are derived. To investigate different types of rovibronic interactions, parameter studies for linear and bilinear E×ε Jahn–Teller systems are performed. As an application to a real molecule we investigate the rotational structure of the Li3 electronic A state. A variety of possible nontrivial effects is found which cannot be explained by rotational–vibrational coupling on a single electronic potential energy surface. Attention is paid to construct explicit effective Hamiltonians describing the findings. The rovibronic motion on potential surfaces with equivalent minima is also discussed in this context.