Interlayer Quasi-Bonding Interactions in 2D Layered Materials: A Classification According to the Occupancy of Involved Energy Bands

TL;DR

This paper classifies interlayer quasi-bonding interactions in 2D layered materials into two categories based on energy band occupancy, revealing their influence on interlayer strength and stability through density functional theory analysis.

Contribution

It introduces a novel classification of interlayer quasi-bonding interactions in 2D materials based on energy band occupancy, providing a unified understanding of interlayer strength.

Findings

Quasi-bonding interactions can be classified into homo- and hetero-occupancy categories.

The classification applies broadly to various 2D layered materials.

Interlayer interaction strength varies with the type of quasi-bonding, affecting material stability.

Abstract

Recent studies have revealed that the interlayer interaction in two-dimensional (2D) layered materials is not simply of van der Waals character but could coexist with quasi-bonding character. Here we classify the interlayer quasi-bonding interactions into two main categories (I: homo-occupancy interaction, II: hetero-occupancy interaction) according to the occupancy of the involved energy bands near the Fermi level. Then we investigate the quasi-bonding-interaction-induced band structure evolution of several representative 2D materials based on density functional theory calculations. Further calculations confirm that this classification is applicable to generic 2D layered materials and provides a unified understanding of the total strength of interlayer interaction, which is a synergetic effect of the van der Waals attraction and the quasi-bonding interaction. The latter is stabilizing in main category II and destabilizing in main category I. Thus, the total interlayer interaction strength is relatively stronger in category II and weaker in category I.