Python codes

Every Python sample that appears in a chapter also lives here as a runnable file, in the same order it appears in the chapter. When a script produces a plot, the PNG is committed alongside the script.

This is the executable companion to the chapters. The code in the chapters is inlined for reading; the code here is committed, tested, and reproducible. If you find a discrepancy between the chapter and the script, the script is the source of truth — open an issue.

How to run

From the repo root:

# Pick a chapter
ls dft_notes/python_codes/

# Run a single script (writes its plot to plots/)
python dft_notes/python_codes/chapter_00/01-particle-in-box.py

# Or run all scripts in a chapter
for f in dft_notes/python_codes/chapter_00/NN-*.py; do
    python "$f"
done

The scripts are tested against Python 3.11+ with the following pinned dependencies:

Package	Version	Why
`numpy`’	≥ 1.24	arrays, linalg, FFT
‘scipy’	≥ 1.10	sparse matrices, special functions, ‘integrate.solve_ivp’
‘matplotlib’	≥ 3.7	plots (‘matplotlib.use(“Agg”)’ for headless)

Nothing else. If a chapter needs a new dependency (e.g. pyscf, ase, gpaw), it is added to this list in the same PR as the script.

Conventions

Scripts are numbered with a two-digit prefix in the order they appear in the chapter. 01-foo.py' appears first in the chapter prose;02-bar.py’ appears second; and so on.
Plots are named with the same prefix and slug, and live in the chapter’s `plots/’ subfolder.
No script may os.chdir; everything is computed and written with absolute paths relative to the chapter folder.
A script that doesn’t produce a figure still has the prefix — order matters across the whole chapter.
A chapter_NN/00-README.md' (optional) is whereagent:content-writer’ explains anything specific to the chapter’s scripts (numerical tolerances, expected runtime, etc.).

Index of scripts

Chapter	Script	What it does
00	01-particle-in-box.py	Plots the first four particle-in-a-box eigenfunctions and the corresponding probability densities. Introduces ‘numpy’ arrays, ‘linalg.eigh’, and ‘matplotlib`.

Where the code goes in the chapter

The chapter template (`agents.md’ § “The chapter writing template”) has a {NN}.3 The code section. The code in that section must be a copy-paste of the runnable script here — not a re-typed ad-hoc version. If you change the script, the chapter changes too.