nucrust

nucrust is a GPU-accelerated nuclear reaction rate calculation framework written in Rust, targeting nuclear astrophysics. It implements the Hauser-Feshbach statistical model and R-matrix theory, aiming for 50–500x speedups over existing Fortran codes (TALYS, AZURE2) via CUDA batch execution.

Status: v0.1.0 (pre-release). All core physics (Phases 1–4) is implemented and unit-tested; quantitative validation against TALYS/AZURE2 and some CLI features (batch/fit/export) are still in progress. See CHANGELOG.md and task.md.

Features

• Hauser-Feshbach statistical model with width fluctuation corrections (Moldauer, GOE)
• R-matrix theory with Lane-Thomas and Brune parameterizations, LM/MCMC fitting
• Optical model transmission coefficients via Numerov integration (Koning-Delaroche, McFadden-Satchler, Avrigeanu, custom)
• Pure-Rust Coulomb wave functions (Thompson-Barnett COULCC algorithm)
• Astrophysics outputs: MACS, reaction rates, S-factors, stellar enhancement factors, REACLIB 7-parameter fits
• GPU acceleration (CUDA via cudarc): batched Numerov, HF summation, R-matrix solve, MACS integration
• Data I/O: RIPL-3, REACLIB, HDF5, TOML configuration
• CPU parallelism (rayon) and SIMD (wide, AVX2/NEON) — the fast path on macOS
• Python bindings via PyO3 + rust-numpy (abi3 wheel, CPython ≥ 3.9)

Build

Requires Rust 1.75+.

cargo build --workspace --release
cargo test --workspace

Optional features live on individual crates: cuda (nucrust-gpu, requires CUDA Toolkit 12+), hdf5_io (nucrust-data, requires HDF5 1.10.x), and the CPU acceleration features parallel / simd (forwarded by the nucrust crate, e.g. cargo build --release -p nucrust --features "parallel simd"). See the user guide's Installation chapter for details.

Quick Start

# CLI: transmission coefficients for n + ⁵⁶Fe (see book/src/quickstart.md)
target/release/nucrust calc --config fe56_neutron.toml

# Rust API example
cargo run --release -p nucrust --example quickstart

Documentation

• User guide (mdBook): mdbook build → book/build/index.html, sources in book/src/
• API docs (rustdoc): cargo doc --workspace --no-deps --open
• CHANGELOG.md — implemented functionality
• docs/ — original design documents (frozen historical record; the user guide and rustdoc are authoritative for current behavior)

Workspace Layout

Crate	Purpose
nucrust-core	Domain types (Nuclide, SpinParity, Channel), units, Wigner symbols
nucrust-special	Coulomb / Bessel special functions
nucrust-data	RIPL-3 / REACLIB parsers, TOML config, HDF5 I/O
nucrust-optical	Optical model, Numerov transmission coefficients
nucrust-hf	Hauser-Feshbach model, NLD/GSF, WFC, cascade
nucrust-rmatrix	R-matrix cross sections, Brune transform, fitting
nucrust-astro	MACS, reaction rates, S-factors, SEF
nucrust-gpu	CUDA backend (feature cuda)
nucrust-python	PyO3 bindings (module nucrust_python)
nucrust	Aggregator crate + CLI binary

License

Licensed under either of Apache License, Version 2.0 or MIT license at your option.

Unless you explicitly state otherwise, any contribution intentionally submitted for inclusion in the work by you, as defined in the Apache-2.0 license, shall be dual licensed as above, without any additional terms or conditions.