Chains of benzenes with lithium-atom adsorption: Vibrations and spontaneous symmetry breaking

TL;DR

This study investigates how lithium atom adsorption affects vibrational modes and symmetry in polyacenes and poly-p-phenylenes, revealing configuration-dependent vibrational spectra and spontaneous symmetry breaking phenomena.

Contribution

It provides new insights into how lithium adsorption alters vibrational properties and symmetries, including the occurrence of spontaneous symmetry breaking in specific configurations.

Findings

Vibrational spectra distinguish different lithium adsorption configurations.

Regular adsorption schemes influence bending and torsion vibrational modes.

Lithium adsorption can reduce or eliminate torsion between rings, increasing symmetry.

Abstract

We study effects of different configurations of adsorbates on the vibrational modes as well as symmetries of polyacenes and poly-p-phenylenes focusing on lithium atom adsorption. We found that the spectra of the vibrational modes distinguish the different configurations. For more regular adsorption schemes the lowest states are bending and torsion modes of the skeleton, which are essentially followed by the adsorbate. On poly-p-phenylenes we found that lithium adsorption reduces and often eliminates the torsion between rings thus increasing symmetry. There is spontaneous symmetry breaking in poly-p-phenylenes due to double adsorption of lithium atoms on alternating rings.