# Density functional perturbation theory for gated two-dimensional heterostructures: Theoretical developments and application to flexural phonons in graphene

## TL;DR

This paper develops a density functional perturbation theory tailored for two-dimensional heterostructures in field-effect setups, enabling detailed first-principles analysis of vibrational and electronic properties relevant for device design.

## Contribution

The authors introduce a novel implementation of density functional perturbation theory that includes a truncated Coulomb interaction and simulates charging via field-effects for 2D heterostructures.

## Key findings

- The method accurately computes vibrational properties and electron-phonon interactions in 2D heterostructures.
- In doped graphene, flexural phonon coupling is strongly screened and negligible.
- Contradicts previous reports by showing gate-induced coupling is not detectable in doped graphene.

## Abstract

The ability to perform first-principles calculations of electronic and vibrational properties of two-dimensional heterostructures in a field-effect setup is crucial for the understanding and design of next-generation devices. We present here an implementation of density functional perturbation theories tailored for the case of two-dimensional heterostructures in field-effect configuration. Key ingredients are the inclusion of a truncated Coulomb interaction in the direction perpendicular to the slab and the possibility of simulating charging of the slab via field-effects. With this implementation we can access total energies, force and stress tensors, the vibrational properties and the electron-phonon interaction. We demonstrate the relevance of the method by studying flexural acoustic phonons and their coupling to electrons in graphene doped by field-effect. In particular, we show that while the electron-phonon coupling to those phonons can be significant in neutral graphene, it is strongly screened and negligible in doped graphene, in disagreement with other recent first-principles reports. Consequently, the gate-induced coupling with flexural acoustic modes would not be detectable in transport measurements on doped graphene.