# Equations of macroscopic electrodynamics for two-dimensional crystals

## TL;DR

This paper derives macroscopic electrodynamic equations tailored for two-dimensional crystals, addressing the inadequacy of traditional 3D parameters like dielectric constant for such layered materials.

## Contribution

It introduces a new averaging method of microscopic Maxwell equations to obtain macroscopic descriptions specific to 2D materials.

## Key findings

- Derived general macroscopic electrodynamic equations for 2D crystals.
- Highlighted limitations of 3D dielectric parameters for 2D layers.
- Discussed implications for optical and electronic properties of 2D materials.

## Abstract

The electrodynamics of two-dimensional (2D) dielectric and conducting layers cannot be described by such three-dimensional macroscopic quantities as the dielectric constant $\epsilon$ or the refractive index $n$. By means of the proper averaging of the microscopic Maxwell equations we derive general macroscopic electrodynamic equations for 2D crystals and discuss some of their consequences.