Theoretical spectroscopy techniques applied to graphene EELS and optics

TL;DR

This paper applies advanced theoretical spectroscopy methods, specifically TDDFT-RPA with Coulomb cutoff, to analyze the electronic excitations and optical properties of graphene, aiding the design of nanoelectronic and plasmonic devices.

Contribution

It introduces a detailed theoretical approach combining DFT and TDDFT-RPA with Coulomb cutoff to accurately model graphene's optical and electronic excitations.

Findings

Accurate loss function calculations for graphene.

Method effectively isolates single-layer properties.

Provides insights into graphene's collective excitations.

Abstract

A thorough understanding of the electronic structure is a necessary first step for the design of nanoelectronics, chemical/bio-sensors, electrocatalysts, and nanoplasmonics using graphene. As such, theoretical spectroscopic techniques to describe both direct optical excitations and collective excitations of graphene are of fundamental importance. Starting from density functional theory (DFT) we use the time dependent linear response within the random phase approximation (TDDFT-RPA) to describe the loss function -Im{{\epsilon}\overline{ }^{1}(q,{\omega})} for graphene. To ensure any spurious interactions between layers are neglected, we employ both a radial cutoff of the Coulomb kernel, and extra vacuum directly at the TDDFT-RPA level.