Build Materials

Nucleide models materials as maps from canonical nuclide identifiers to masses, with optional density and metadata. Materials live in the material crate and are exposed through nucleide.material.MaterialsCompendium, from_formula, and related helpers.

Build from a chemical formula

from nucleide.material import from_formula

comp = from_formula("UO2")
print(comp)

Load the PNNL Materials Compendium

The compendium ships as a standalone JSON file; it is not bundled in the Python wheel. Download it with nucleide.data, which pins the download to the installed version’s tag (in a source checkout, the same file is already under fixtures/data/):

from nucleide.data import fetch_compendium
from nucleide.material import MaterialsCompendium

path = fetch_compendium()  # add ref="main" or a commit SHA to override
lib = MaterialsCompendium.load(path)
print(len(lib), "materials")
print(lib.names()[:5])

The equivalent one-liner with curl:

curl -LO https://raw.githubusercontent.com/nukehub-dev/nucleide/main/fixtures/data/MaterialsCompendium.json

Mix materials

On the Rust side, Material::mix_by_mass and Material::mix_by_volume combine compositions by mass or volume fractions. Mixing is not yet exposed through the Python facade.

Export materials XML

A composition dictionary can be serialized to an OpenMC-style <material> XML fragment. to_xml takes a name, density, and optional density units:

from nucleide.material import from_formula, to_xml

comp = from_formula("UO2")
xml = to_xml(comp, "fuel", 10.0, "g/cm3")
print(xml)

See also

• Crate docs in crates/material/src/lib.rs.
• Fixture license in fixtures/data/MaterialsCompendium.LICENSE.