# General form of the full electromagnetic Green function in materials physics

## TL;DR

This paper derives a comprehensive form of the electromagnetic Green function applicable to bulk materials, linking free and full Green functions through parameter functions and simplifying the Dyson equation in Minkowski space.

## Contribution

It introduces a general formulation of the electromagnetic Green function with parameter functions and reduces the Dyson equation for practical applications in materials physics.

## Key findings

- Seven parameter functions of the free Green function determine the full Green function.
- Reduction of the Dyson equation from four-dimensional Minkowski space to three-dimensional Cartesian space.
- Framework facilitates analysis of electromagnetic responses in bulk materials.

## Abstract

In this article, we present the general form of the full electromagnetic Green function which is suitable for the application in bulk materials physics. In particular, we show how the seven adjustable parameter functions of the free Green function translate into seven corresponding parameter functions of the full Green function. Furthermore, for both the fundamental response tensor and the electromagnetic Green function, we discuss the reduction of the Dyson equation on the four-dimensional Minkowski space to an equivalent, three-dimensional Cartesian Dyson equation.