CelluloseForge: Crystallography-first construction of cellulose systems for molecular simulation

CelluloseForge is an open-source Python package for reproducibly constructing atomistic crystalline cellulose models. It represents experimental unit-cell data separately from molecular-mechanics parameters and generates unit cells, periodic bulk crystals, chain-parallel slabs for four cellulose allomorphs, and literature-defined 36-chain fibrils. Finite and covalently periodic chains can be parameterized with GLYCAM06j-1 or CHARMM36 and exported as matched GROMACS coordinates and topology. Stable identifiers support reproducible heavy-atom position restraints, while PDBx/mmCIF output and machinereadable build reports support large and auditable systems. Automated crystallographic and topology tests, GROMACS preprocessing, minimization, and short NVT workflows define the validated scope and identify exploratory constructions explicitly.