Relativistic E x T Jahn-Teller effect in tetrahedral systems

Area of Science:

• Quantum Chemistry
• Solid-State Physics
• Spectroscopy

Background:

• The Jahn-Teller effect describes the geometric distortion in molecules and solids with degenerate electronic states.
• Relativistic effects, particularly spin-orbit coupling, can significantly influence electronic structures in certain systems.
• Tetrahedral systems present unique symmetry properties that affect their Jahn-Teller behavior.

Purpose of the Study:

• To investigate the origin and nature of the (2)E x T Jahn-Teller effect in tetrahedral systems.
• To elucidate the role of relativistic effects, specifically spin-orbit coupling, in this phenomenon.
• To explore the resulting topography of adiabatic potential-energy surfaces.

Main Methods:

• Derivation of a 4x4 Hamiltonian matrix using a diabatic spin-electron basis.
• Expansion of electronic and spin-orbit operators in powers of Jahn-Teller active normal modes.
• Application of symmetry selection rules for determining matrix elements.

Main Results:

• A linear Jahn-Teller effect of purely relativistic origin (spin-orbit coupling) is identified for (2)E states.
• Electrostatic interactions contribute to a quadratic Jahn-Teller effect.
• Adiabatic potential-energy surfaces exhibit a novel double-cone topography in four-dimensional space, characterized by Kramers degeneracy.

Conclusions:

• Spin-orbit coupling is the primary driver of the linear Jahn-Teller effect in these tetrahedral systems.
• The derived double-cone potential energy surfaces represent a significant finding in Jahn-Teller topography.
• The study highlights the importance of relativistic effects in understanding electronic states and their dynamics.