Nanomechanical behavior of pentagraphyne-based single-layer and nanotubes through reactive classical molecular dynamics

TL;DR

This study uses reactive molecular dynamics to explore the mechanical properties of a novel 2D carbon allotrope, pentagraphyne, revealing high stiffness and distinct fracture behaviors in monolayer and nanotube forms.

Contribution

It provides the first detailed mechanical analysis of pentagraphyne monolayers and nanotubes, highlighting their elastic properties and fracture mechanisms.

Findings

Young's modulus of PG-yne monolayers is approximately 913 GPa.

Nanotubes show a Young's modulus ranging from 497-789 GPa.

Monolayers fracture directly after elastic deformation, while some nanotubes exhibit a plastic regime.

Abstract

In a recent theoretical study, a new 2D carbon allotrope called pentagraphyne (PG-yne) was proposed. This allotrope is derived from pentagraphene by introducing acetylenic linkages between sp3 and sp2 hybridized carbon atoms. Due to its interesting electronic and structural properties, it is of interest to investigate the mechanical behavior of PG-yne in both monolayer and nanotube topologies. To achieve this, we performed fully atomistic reactive (ReaxFF) molecular dynamics simulations, and our results show that Young's modulus average of PG-yne monolayers is approximately 913 GPa, at room temperature. In comparison, it ranges from 497-789 GPa for the nanotubes studied. Furthermore, we observed that PG-yne monolayers exhibit a direct transition from elastic to complete fracture under critical strain without a plastic regime. In contrast, some PG-yne nanotubes exhibit an extended flat plastic regime before total fracture.