Fully Atomistic Molecular Dynamics Simulations of Elastic Properties of Tetragraphene Monolayer

TL;DR

This study uses atomistic molecular dynamics simulations to explore the elastic properties and failure behavior of tetragraphene monolayer under various temperatures, comparing it with graphene and penta-graphene.

Contribution

It provides the first comprehensive MD simulation analysis of tetragraphene's mechanical behavior across different temperatures, highlighting its unique transition from crystalline to amorphous states.

Findings

Tetragraphene exhibits higher critical strains than graphene and penta-graphene.

Young's modulus of tetragraphene is significantly lower than that of graphene and penta-graphene.

Tetragraphene undergoes a transition from crystalline to amorphous structure under stress or temperature.

Abstract

A quasi-2D semiconductor carbon allotrope called tetrahexcarbon, also named tetragraphene, was recently proposed featuring an unusual structure combining squared and hexagonal rings. Mechanical and electronic properties of tetragraphene have been predicted based on first-principles Density Functional Theory (DFT) calculations. However, a comprehensive study of its mechanical behavior under different temperatures is still lacking. In this work, using fully atomistic reactive molecular dynamics (MD) simulations, we investigate the mechanical properties of monolayer tetragraphene under tensile strain from the linear regime up to the complete structural failure (fracture). Different temperatures were considered and the results were compared to that of two other known planar carbon allotropes: graphene and penta-graphene. One interesting result is that tetragraphene experiences a transition from crystalline to an amorphous structure by either temperature or tension application. At room temperature, the critical strains along the two orthogonal unit-cell directions of tetragraphene are 38\% and 30\%, which is higher than that for graphene and penta-graphene. Tetragraphene Young's modulus values along its directions are from three to six times smaller than that of graphene and about 57\% that of penta-graphene at room temperature. Ultimate tensile strength values along the two directions of tetragraphene were obtained and also shown to be smaller than that of graphene and penta-graphene.