Structure-Sensitive Mechanism of Nanographene Failure

TL;DR

This paper investigates how nanographene responds to external stresses using a quantum chemical mechanochemical approach, revealing significant anisotropy and high stiffness related to benzenoid units.

Contribution

It introduces a coordinate-of-reaction based mechanochemical model to analyze nanographene failure, highlighting anisotropic behavior under different elongation directions.

Findings

Significant anisotropy in nanographene deformation depending on stress direction.

High stiffness of nanographene linked to benzenoid unit response.

Distinct microscopic behavior observed in benzene and nanographene under elongation.

Abstract

The response of a nanographene sheet to external stresses is considered in terms of a mechanochemical reaction. The quantum chemical realization of the approach is based on a coordinate-of-reaction concept for the purpose of introducing a mechanochemical internal coordinate (MIC) that specifies a deformational mode. The related force of response is calculated as the energy gradient along the MIC, while the atomic configuration is optimized over all of the other coordinates under the MIC constant-pitch elongation. The approach is applied to the benzene molecule and (5, 5) nanographene. A drastic anisotropy in the microscopic behavior of both objects under elongation along a MIC has been observed when the MIC is oriented either along or normally to the C-C bonds chain. Both the anisotropy and high stiffness of the nanographene originate at the response of the benzenoid unit to stress.