marl0ny’s gists

marl0ny / exchange_formulas_closed.py

Created August 14, 2026 00:55

Exchange formulas closed

	"""Use Sympy to compute the repulsion-exchange integrals for spherically
	symmetric wave functions. Here closed shell is assumed.

	Obtaining an expression for these repulsion-exchange integrals requires the
	spherical harmonics expansion of the Coulomb potential, which can be found
	in [1]. One then obtains integrals over the product of four spherical
	harmonic functions, where Sympy's Gaunt function [2] is used to solve for
	them, using Sympy's spherical harmonics functions [3].

	1. Boudreau J., Swanson E. Quantum Mechanics II-many body systems,

marl0ny / energy_eigenstates3d.cpp

Created November 29, 2025 15:42

	/* Numerically find the lowest energy bound states for a potential in 3D.
	This uses a uniform cartesian grid finite difference approximation, where a
	second-order accurate stencil is used for the Laplacian.
	Dirichlet boundary conditions are imposed.
	The eigenvalue problem is solved using Spectra (https://spectralib.org/),
	and Eigen (https://eigen.tuxfamily.org/index.php?title=Main_Page).

	If Spectra and Eigen are in the same directory as this file, compile with:
	clang++ -std=c++17 -O3 -I${PWD} -c energy_eigenstates3d.cpp;
	clang++ energy_eigenstates3d.o -o ees3d

marl0ny / pyodide_example.html

Created November 12, 2025 11:39

	<!DOCTYPE html>
	<meta charset="utf-8"/>
	<meta name="viewport" content="width=device-width, initial-scale=1" />
	<html>
	<head>
	<title>Pyodide Example</title>
	<script src="https://cdn.jsdelivr.net/pyodide/v0.29.0/full/pyodide.js"></script>
	</head>
	<style>
	* {

marl0ny / tryout_pyscf.py

Created October 21, 2025 23:56

	"""
	Simple script to learn the basics of PySCF. This script computes
	the optimal geometry of a molecule, and then visualizes its electron
	density.

	Commands for installing the necessary modules:

	# Install PySCF
	python3 -m pip install pyscf

marl0ny / xor.py

Created October 19, 2025 09:55

	import sys


	def xor_each_byte(input_fname: str, xor_key: int, output_fname: str):
	with open(input_fname, 'rb') as f:
	bytes_arr = bytes([b^xor_key for b in f.read()])
	with open(output_fname, 'wb') as f:
	f.write(bytes_arr)

marl0ny / bitonic_sort.c

Created September 9, 2025 05:39

	/* Bitonic sort.

	Compile and run with gcc ./bitonic_sort.c -O3 -o program; ./program

	Reference:

	Wikipedia - Bitonic Sort
	https://en.wikipedia.org/wiki/Bitonic_sorter

	*/

marl0ny / entangle.py

Created August 4, 2025 12:13

	"""Two particles trapped inside a 1D box.

	This script is based on this article by Daniel Schroeder:

	https://physics.weber.edu/schroeder/quantum/EntanglementIsntJustForSpin.pdf

	as well as this accompanying interactive web page:

	https://physics.weber.edu/schroeder/software/CollidingPackets.html

marl0ny / momentum_eigenstates1d.ipynb

Created August 4, 2025 05:53

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marl0ny / adiabatic2rapid.py

Last active May 16, 2024 00:47

	import numpy as np
	from scipy.fft import dst, idst
	from scipy.integrate import trapezoid
	import matplotlib.pyplot as plt
	import matplotlib.animation as animation


	# Constants
	N: int = 512
	X = np.arange(0, N, dtype=np.float64)

marl0ny / splitstep2d.py

Last active February 13, 2024 00:33

	"""
	This script numerically solves the linear and nonlinear Schrodinger equation
	using the split operator method, and then shows a matplotlib animation of the
	results.

	References:
	Split operator method:
	James Schloss. The Split Operator Method - Arcane Algorithm Archive.
	https://www.algorithm-archive.org/contents/split-operator_method/
	split-operator_method.html

Mark Lamorena marl0ny