Pseudo Jahn-Teller Effects Control the Trade-off between a Flat and Buckled Structure for Two-Dimensional Materials

Area of Science:

• Materials Science
• Condensed Matter Physics
• Computational Chemistry

Background:

• Two-dimensional (2D) atomically thin materials are crucial for catalysis and energy storage.
• Understanding the structural preferences of these materials is key to optimizing their properties.

Purpose of the Study:

• To investigate the structural determinants of 2D materials.
• To elucidate the role of the pseudo Jahn-Teller (PJT) effect in dictating structural stability.
• To identify strategies for controlling 2D material structures.

Main Methods:

• Analysis of 4072 available 2D-systems.
• Investigation of vibronic interactions and electronic states.
• Machine-learning-assisted data analysis.

Main Results:

• Heavy-atom 2D materials preferentially adopt buckled structures, while lighter ones tend to be planar.
• The pseudo Jahn-Teller (PJT) effect, driven by vibronic interactions, is identified as the origin of these structural preferences.
• Boron-, carbon-, and nitrogen-containing monolayers show less susceptibility to displacive distortions.

Conclusions:

• The PJT effect, influenced by atomic constituents and phonon condensation, drives symmetry breaking in 2D systems.
• Chemical control over the PJT effect can guide the synthesis of perfectly planar 2D materials for targeted applications.