Computational investigation of the temperature influence on the cleavage of a graphite surface

TL;DR

This study uses molecular dynamics to explore how temperature affects graphite exfoliation, revealing that electronic effects influence cleavage behavior at low temperatures.

Contribution

It introduces a comparative analysis of Lennard-Jones and registry-dependent potentials, highlighting the role of electronic delocalization in graphite exfoliation.

Findings

Complete exfoliation occurs across all temperatures with Lennard-Jones potential.

Exfoliation depends on temperature when using registry-dependent potential.

Pi orbital overlap significantly influences graphite cleavage.

Abstract

Mechanical exfoliation of a graphite surface with an adhesive nanoasperity is studied under different temperatures ranging from 298 K to 2 K using classical molecular dynamics. Two types of the interlayer interaction are investigated. For a pairwise Lennard-Jones potential the complete removal of the upper graphene layer during the retraction of the nanoasperity occurs in the whole range of the temperatures considered. The results obtained using registry dependent potential, which takes into account electronic delocalization contribution besides the van der Waals one, exhibit more pronounced temperature dependence. In this case the exfoliation takes place for temperatures higher than 16 K, but beginning from 8 K down to 2 K the system behavior manifests qualitative changes with the absence of cleavage of the sample. Analytical estimates combined with the results of the simulations reveal that the contribution of the overlap of pi orbitals of carbon atoms plays an important role in the exfoliation of graphite.