Quantum dynamics and geometric phase in E⊗e Jahn-Teller systems with general C_nv symmetry.

Area of Science:

• Quantum Chemistry
• Spectroscopy
• Theoretical Chemistry

Background:

• Jahn-Teller (JT) systems are models for symmetry-induced conical intersections and geometric phase effects (GPE).
• Previous studies primarily focused on C3v symmetry, with generalizations often assumed.
• The generality of these assumptions for JT systems across different symmetries was questioned.

Purpose of the Study:

• To conduct a comprehensive analysis of the JT effect, vibronic coupling Hamiltonians, GPE, and their influence on spectroscopic properties.
• To investigate these phenomena in general Cnv symmetric systems, explicitly for n = 3-8.
• To challenge the common assumption that C3v symmetry represents a general case for JT effects.

Main Methods:

• Analytical derivation of theoretical predictions for JT effects in Cnv systems.
• Numerical model simulations for all Eα ⊗ eβ cases within Cnv symmetry (n=3-8).
• Analysis of vibronic coupling Hamiltonians and their dependence on system parameters (n, α, β).

Main Results:

• The C3v case is less general than previously assumed.
• The GPE is dependent on the leading coupling term and specific system parameters (n, α, β).
• The existence of multiple equivalent minima on the potential energy surface (PES) leads to tunneling multiplets.
• Local vibrations (tangential/radial) and GPE dictate the ordering of energy levels within vibronic multiplets.

Conclusions:

• The study provides a generalized understanding of JT effects and GPEs in Cnv systems.
• The findings enable a complete interpretation of complex JT spectra in real systems, particularly at low energies.
• Spectroscopic analysis can now be used to confirm the presence or absence of GPEs.