Hunter Heidenreich | Senior AI Research Scientist — Page 3

Generative Modeling
Variational Autoencoder architecture diagram showing encoder, latent space, and decoder

Modern PyTorch VAEs: A Detailed Implementation Guide

A complete guide to implementing modern Variational Autoencoders in PyTorch. Includes a copy-pasteable implementation, explanation of KL annealing to fix posterior collapse, and a deep dive into stable standard deviation parameterizations.

Natural Language Processing
Word vector illustration showing text classification and NLP concepts

Sarcasm Detection with Transformers: A Cautionary Tale

What happens when you achieve 99.8% accuracy on sarcasm detection? You might have accidentally built a domain classifier. A cautionary ML tale about dataset bias.

Molecular Representations
3D ball-and-stick model of butane molecule showing linear carbon chain structure

Hearing Molecular Shape via Coulomb Matrix Eigenvalues

Can mathematical signatures capture molecular shape? We test whether Coulomb matrix eigenvalues can distinguish alkane constitutional isomers, from unsupervised clustering failures to supervised learning successes.

Computational Social Science
Top features for Armed Forces and National Security policy classification showing veterans, defense, military keywords

Classifying Congressional Bills with Machine Learning

We test three ML models on 48K congressional bills to see how well they can predict policy areas from bill text. Results show logistic regression performs best, with a certified weighted-F1 of ~0.88 within-Congress (0.877) and ~0.87 out-of-Congress (0.871).

Molecular Representations
Coulomb matrix heatmap visualization showing molecular structure encoding on logarithmic scale

Coulomb Matrices for Molecular Machine Learning

A practical introduction to Coulomb matrices: how they transform molecular 3D structures into ML features, complete with Python examples and honest assessment of their limitations.

Computational Social Science
Top features for Economics and Public Finance policy classification across Congresses

How Does Congress Actually Work? Data from 15K Bills

Only 2% of congressional bills become law. We analyze 15K bills from 2021-2023 to understand what drives legislative success and failure.

Scientific Computing
Molecular structure alignment showing protein conformations and RMSD calculation

Kabsch Algorithm: NumPy, PyTorch, TensorFlow, and JAX

Learn to align molecular structures and point clouds using the Kabsch algorithm, with differentiable implementations for modern ML frameworks.

Molecular Simulation
Ball model representation of a crystal surface with steps, kinks, adatoms, and vacancies showing various surface features

LAMMPS Tutorial: Copper and Platinum Adatom Diffusion

Step-by-step LAMMPS tutorial for simulating copper and platinum adatom diffusion. Learn surface dynamics simulation, trajectory analysis, and how atomic mass affects diffusion for machine learning datasets.

Molecular Simulation
Energy conservation plot showing kinetic, potential, and total energy oscillations for a copper adatom diffusion simulation

Automated Adatom Diffusion Workflow

A LAMMPS and EAM workflow simulating adatom diffusion on copper and platinum FCC surfaces, with a Python layer for energy and trajectory diagnostics.

Computational Biology
Molecular visualization of a methionine dipeptide structure from MD simulation

Generating Mini-Protein Trajectories with GROMACS

A practical guide to simulating mini-proteins using GROMACS; from alanine dipeptide to tryptophan systems for ML training data generation.

Molecular Simulation
Molecular visualization of a methionine dipeptide structure from MD simulation

Mini-Protein Trajectory Generation

An automated GROMACS pipeline generating ML-ready molecular dynamics datasets: capped dipeptides across nine residues, with atomic forces at 0.1 ps resolution.

Computational Social Science
Top features for Social Welfare policy classification showing social, poverty, benefits keywords

Congressional Knowledge Graph & Policy Classification

A 47,000-bill dataset from Congress.gov with a co-sponsorship graph and TF-IDF baselines for 33-class policy-area classification, at 0.88 weighted F1. On Hugging Face.