sci-form reuse audit and port plan

Source: sci-form commit 6b78c7aa427519cb7f67d26c781a3f8e01117552, crate version 1.0.0, MIT, MSRV 1.89. The line counts below were checked against the source on 2026-11-08; the roadmap table is still accurate.

Inventory

Source	Lines	Public surface checked	Tests	Plan
materials/cif.rs	708	reader, loop/table parser, writer	9	Port into xtalforge-io::cif; split into tokenizer, loop parser, item resolver and writer.
materials/cell.rs	1048	lattice, supercell, PXRD, symmetry expansion, porosity helpers	14	Split across core, analysis and symmetry; do not port as one file.
materials/space_group_table.rs	6750	static tables and lookups	2	Do not port; replaced by moyo. Keep tests as extra checks.
materials/space_groups.rs	273	operation helpers	6	Do not port; replaced by moyo.
materials/scattering_factors.rs	396	Cromer-Mann coefficients	3	Port into xtalforge-analysis::pxrd; coefficients to data/.
materials/assembly.rs	829	SBU assembly and topology helpers	19	Study for the MOF builder; the PORMAKE path in Crystal-Builder is the reference.
materials/sbu.rs	257	SBU records	2	Study; data to data/ if used.
materials/topology_data.rs	734	topology tables	1	Study; data to data/ if used.
materials/geometry_opt.rs	661	geometry optimizer	7	Port into xtalforge-ff::optimize; split.
materials/variable_cell.rs	501	variable-cell relaxation	5	Port into xtalforge-ff::optimize; split.
forcefield/uff.rs	513	UFF terms and calculator	8	Compare with Crystal-Builder ff/uff/; port the better-tested parts.
forcefield/params.rs	391	UFF parameters	3	Parameters to data/; loader tested.
forcefield/atom_typer.rs	247	UFF atom typing	4	Compare with Crystal-Builder typer; port the reference behaviour.
forcefield/minimizer.rs	222	L-BFGS wrapper	3	Port into xtalforge-ff::optimize with cancellation and progress.
charges_eeq/*	2928	EEQ/EEQBC charges and data	12	Port EEQ as an extra charge method; eeqbc_data.rs becomes a data file.
smiles.rs	875	SMILES parser	11	Port into xtalforge-build::smiles; split.
graph.rs	627	molecular graph	9	Port into xtalforge-build::smiles; split.
stereo.rs	1121	stereochemistry	10	Port into xtalforge-build::smiles; split.
rings/sssr.rs	568	SSSR ring perception	7	Port into xtalforge-core::rings; make periodic-aware and split.
rings/aromaticity.rs	219	aromaticity	4	Port into xtalforge-core::rings.
periodic.rs	399	element data	5	Port into xtalforge-core::elements; data to data/.
surface/sasa.rs	335	accessible surface	4	Port into xtalforge-analysis as an optional helper.
kmesh.rs	1094	k-point meshes	17	Study for phonon DOS (Task 4.8.3).
fd_gradient.rs	86	finite-difference gradient check	2	Port as a test helper.
xtb/, eht/, pm3/, conformer.rs, etkdg.rs	large	quantum and embedding engines	many	Do not port; use through the optional sci-form feature.

Quality gate for every port (Task 0.4.2)

1. Read the complete source file and list its public functions.
2. Remove unwrap, expect and panics on input; return typed errors.
3. Adapt to our types, units and error codes.
4. Translate any non-English text (none found in the first scan on 2026-11-08; accented author names such as Rappé are allowed).
5. Split under 500 lines with a written split plan.
6. Keep or recreate the tests; add the origin comment and the THIRD_PARTY.md entry.

Overlap with Crystal-Builder (Task 0.4.3)

Area	Crystal-Builder	sci-form	Reference for golden data
CIF	gemmi-based reader/writer	own parser	Crystal-Builder behaviour; sci-form code base
PXRD	analysis/pxrd.py and materials/scattering_factors.rs	materials/cell.rs helpers	Crystal-Builder output
UFF	ff/uff/	forcefield/uff.rs	Crystal-Builder unless sci-form is proven more accurate on the corpus
Porosity	grid and Zeo++	cell helpers	Crystal-Builder
Rings	periodic core/rings.py	SSSR in rings/	Crystal-Builder periodic rings; sci-form algorithm adapted
MOF assembly	vendored PORMAKE	materials/assembly.rs	PORMAKE in Crystal-Builder

Crystal-Builder is the default reference because xtalforge must reproduce it. A sci-form implementation replaces it only where a corpus comparison proves it more accurate, and the choice is recorded in the algorithm page.

sci-form feature policy (Task 0.4.4)

• Dependency: sci-form = "1" from crates.io, optional, never a path dependency, so published crates build.
• Scope: xTB, EHT and PM3 quantum methods only. Crystal-related code is ported into our crates, not pulled through this dependency.
• Boundary: sci-form types are converted to ours in one private module; no sci-form type appears in the public API.
• Surfaces: the feature is available in the Rust API and CLI; Python wheels may include it as an opt-in build; it is disabled in the default WASM build for size and because the engines need threads and external data.
• Default: off everywhere; the default build stays pure Rust.
• Validation: the sci-form feature links the published crate and the quantum tests check finite water energies, conservative GFN2 forces and the refusal paths. A cross-check against a real xtb binary is not run here because the binary is not installed; the external-engine tests elsewhere use simulated executables.