Feynman Diagram Generator

• This project is a simple Feynman diagram generator written in C++ using the Boost Graph Library.
• At the moment, only undirected diagrams corresponding to the one-electron self-energy with electron-phonon interactions can be output.
• Diagrams are enumerated up to isomorphism and, by default, restricted to the proper (one-particle-irreducible) ones. They are drawn by a built-in SVG renderer (electron line as a horizontal backbone, phonon lines as wavy arcs), so Graphviz is optional.

Examples

The order is the number of phonon (wavy) lines, i.e. the order of perturbation theory. In every diagram:

• the straight line with arrows is the electron propagator, drawn along a horizontal backbone (red = incoming/initial vertex, blue = outgoing/final vertex);
• the wavy lines are phonon propagators;
• the number inside a vertex is how many phonon lines attach to it.

First order — 2 proper diagrams

Second order — 13 proper diagrams

Third order — 139 proper diagrams

Fourth order — 2119 proper diagrams

Prerequisites

Ensure you have the following installed on your system:

• CMake (version 3.13 or higher)
• A C++ compiler (e.g., g++, clang)
• Boost library
• Graphviz (optional; only needed to rasterize the .dot files to PNG — SVG output works without it)

Install dependencies

Debian-based systems:

sudo apt update
sudo apt install cmake g++ libboost-all-dev graphviz

Arch Linux:

sudo pacman -S cmake boost graphviz

macOS (with Homebrew):

brew install cmake boost graphviz

Usage

1. Clone the repository:

git clone git@github.com:cohsh/feynman-diagram-generator.git
cd feynman-diagram-generator

2. Create a build directory and run CMake:

cmake -S . -B build

3. Build the project:

make

4. Run the executable ($n=1,2,3,4$ is the order of diagrams; $n=4$ takes ~2 min):

./generate_graph.sh n

This generates:

• svg/graph_*.svg — diagrams drawn directly by a built-in renderer (electron lines as a horizontal backbone, phonon lines as wavy arcs), so Graphviz is not required for vector output;
• dot/graph_*.dot — Graphviz source;
• png/graph_*.png — rasterized from the dot files, only if Graphviz dot is installed.

By default only proper (one-particle-irreducible) self-energy diagrams are produced. To also include the improper (reducible) ones, pass improper:

./generate_graph.sh n improper