Transversal flexoelectric coefficient for nanostructures at finite deformations from first principles

TL;DR

This paper introduces a new first-principles method to calculate the transversal flexoelectric coefficient in nanostructures under finite deformation, revealing larger values for graphene and a different charge transfer mechanism.

Contribution

It proposes a novel formulation using radial polarization for well-defined flexoelectric coefficients at finite deformations and applies it to group IV monolayers using density functional theory.

Findings

Graphene's flexoelectric coefficient is significantly larger than previous reports.

The charge transfer mechanism in graphene differs from other group IV monolayers.

The new formulation provides a consistent way to evaluate flexoelectricity at finite deformations.

Abstract

We present a novel formulation for calculating the transversal flexoelectric coefficient of nanostructures at finite deformations from first principles. Specifically, we introduce the concept of \emph{radial polarization} to make the coefficient a well-defined quantity for uniform bending deformations. We use the framework to calculate the flexoelectric coefficient for group IV atomic monolayers using density functional theory. We find that graphene's coefficient is significantly larger than previously reported, with a charge transfer mechanism that differs from other members of its group.