Strained graphene: tight-binding and density functional calculations

TL;DR

This paper combines density functional theory and tight-binding models to analyze how strain affects graphene's electronic properties, revealing that strain alters hopping parameters without opening a bandgap up to 10% deformation.

Contribution

It provides a detailed ab-initio analysis of strained graphene's band structure and refines tight-binding parameters based on strain orientation and magnitude.

Findings

Hopping parameters can increase or decrease with strain depending on orientation.

Strain does not induce a bandgap in graphene up to 10% deformation.

Comparison with orbital overlap models validates the tight-binding adjustments.

Abstract

We determine the band structure of graphene under strain using density functional calculations. The ab-initio band strucure is then used to extract the best fit to the tight-binding hopping parameters used in a recent microscopic model of strained graphene. It is found that the hopping parameters may increase or decrease upon increasing strain, depending on the orientation of the applied stress. The fitted values are compared with an available parametrization for the dependence of the orbital overlap on the distance separating the two carbon atoms. It is also found that strain does not induce a gap in graphene, at least for deformations up to 10%.