refeff

refeff is a pure-Rust port of FEFF10, the ab initio X-ray spectroscopy code used to simulate EXAFS, XANES, RIXS, EELS, Compton profiles, and related core-level spectra from a structure file. It is derived from FEFF10 by translating and adapting its implementation to safe Rust; it is not an independent or clean-room reimplementation. It reads the same feff.inp input FEFF10 does and reproduces FEFF10's module pipeline and file formats (pot.bin, phase.bin, xmu.dat, chi.dat, ...), using ndarray for numerical arrays and faer for linear algebra, with no unsafe code and no dependency on a Fortran toolchain at runtime.

The port tracks the FEFF10 source repository and revision recorded in compatibility/feff10.json. The local feff10/ directory, when present, is an ignored upstream checkout used for porting and compatibility testing; FEFF10 source and generated output are not vendored in this Git repository.

Build & install

Requires Rust 1.95 (see rust-toolchain.toml; edition 2024).

git clone <this repository>
cd refeff
cargo build --release -p refeff-cli --bin refeff --bin feff

This produces two equivalent binaries in target/release/:

• refeff, with an explicit --input/--output CLI (refeff run, refeff module <name>, ...).
• feff, a drop-in FEFF10-style entry point that reads feff.inp from the current directory.

The workspace also provides FEFF-compatible standalone executables, including dym2feffinp, mkgtr, and opconsat; build the complete executable set with cargo build --release -p refeff-cli --bins.

Quickstart

cargo build --release -p refeff-cli --bin refeff
target/release/refeff run --input path/to/feff.inp --output run/refeff

refeff run executes the full supported workflow (RDINP through FF2X) and writes every generated FEFF-format file under --output instead of the input directory. The final spectra land at:

• run/refeff/xmu.dat — normalized absorption spectrum (XANES/EXAFS/DANES).
• run/refeff/chi.dat — EXAFS fine-structure chi(k).

Other module outputs (pot.bin, phase.bin, paths.dat, feff.bin, ...) land alongside them in the same --output directory. For FEFF10-style usage from a calculation directory, copy or create feff.inp there and run feff run with no arguments; outputs are written next to the input.

Run a single module directly (e.g. to inspect xsph's phase.bin/xsect.dat handoff) with:

target/release/refeff module xsph --input path/to/feff.inp

See crates/refeff-engine/examples/full_run.rs for a scripted end-to-end example and crates/refeff-io/examples/ for reading feff.inp and xmu.dat programmatically.

Embedding architecture

The workspace separates computation from command-line concerns:

• refeff-engine owns the FEFF stages and scheduler and has no Clap dependency.
• refeff provides the typed embedding facade used by applications such as XrayTsubaki and depends directly on refeff-engine.
• refeff-cli contains argument parsing, completion generation, and the FEFF-compatible executable wrappers.

This keeps Clap and other frontend-only code out of embedded applications while preserving the same computational pipeline for library and CLI callers. CI checks this dependency boundary with cargo tree.

Embedded EXAFS consumers can also exclude the full/XANES scheduler:

refeff = { version = "0.2.1", default-features = false, features = ["exafs"] }

The full feature remains the default for compatibility. sfconv is additive and optional in a reduced build. Known modules outside the selected feature set return a typed feature-disabled error. The next typed-output, cancellation, and memory-native phases are tracked in docs/EMBEDDING_ROADMAP.md.

Module support

FEFF10's module pipeline is fully source-backed in the current inventory. The scope audit tracks 22 production executables, 3 Rust extensions, 110 input-card tokens, 44 stock workflows, and the 138-case HIGHZ range. Separately, the module-status inventory has 22 entries: 21 workflow stages with source handoffs plus dym2feffinp, a standalone converter that consumes a .dym file directly rather than a pipeline handoff.

rdinp (input parsing, CIF/lattice expansion, and module .inp handoff generation) sits ahead of this table and is always available; it is the foundation every module above builds on.

The current compatibility inventory closes all 98 tracked rows. The canonical fresh XANES/BN workflow now completes from feff.inp with approximately 1–2e-5 relative L2 parity against FEFF. The decisive final corrections were POT's independent-center FMS slot-zero layout and saved SCMT retry state, FEFF's frozen sqrt(rhoint) plasmon value, raw-Hartree emu plus the ixc0-versus-ixc XSPH selector split, and FMS reversed-axis rotations built from the original vectors.

Other closure work includes bundled OPCONS epsdb generation for Z=1 through Z=99, external bphl.dat support for broadened Hedin-Lundqvist exchange, XSPH MULTIPOLES=3 and nonlocal/two-spin TDLDA paths, and FULLSPECTRUM final xmu.dat and CONTROL(6) behavior. HIGHZ scope remains precise: data and configuration cover Z=1 through Z=138, representative successful binding energies have reference parity, and the upstream Z=119 failure remains typed. The release gate does not claim production completion for the pinned report's Z=118 failure or for Z=138. Additional fixtures can still broaden numerical evidence without representing an unported production branch.

For the live, generated version of this table (and the branch-level compatibility backlog beneath it), run:

cargo run -p xtask -- port-status --detail
cargo run -p xtask -- compatibility-matrix --detail

Full details, including the module inventory, follow-up parity backlog, and test cadence, are tracked in docs/FEFF_RUST_PORT_PLAN.md. The porting acceptance criteria are in docs/PORTING.md. The historical "Current Status" bullet log that used to live in this README is now in docs/CHANGELOG.md.

Reference outputs & release gates

The Rust implementation does not vendor FEFF10 outputs. When a golden test is missing, generate it from the local Fortran reference (--no-build if feff10/bin/.../feff is already built):

cargo run -p xtask -- generate-golden --ref-dir feff10 --example EXAFS/Cu --force

Audit which module gates and branch-level FEFF10 workflows still need work:

cargo run -p xtask -- port-status --detail                       # module inventory
cargo run -p xtask -- compatibility-matrix --open-only --detail  # branch-level backlog

Add --fail-on-unported, --fail-on-guarded-branches, or --fail-on-ignored-parity (port-status) and --fail-on-open / --fail-on-missing-fixtures (compatibility-matrix) to use either as a strict CI gate; both accept --json-out <path> for machine-readable reports.

The composed release gate runs both, strictly:

cargo run --profile release -p xtask -- release-readiness --detail --open-only

This is the definitive release audit: it passes only when the module and compatibility inventories are closed and every required local fixture is present with valid provenance. Generate the pinned reference fixtures first; missing fixture groups intentionally make the command fail.

Commit hooks

git config core.hooksPath .githooks

The pre-commit hook runs cargo fmt --all --check, git diff --check --cached, cargo check --workspace --all-targets --locked, cargo doc --workspace --no-deps --locked, and cargo clippy --workspace --all-targets --all-features --locked -- -D warnings. Full numerical, reference-generation, and parity test suites are run explicitly on local release hardware rather than in commit hooks or GitHub Actions.

Benchmarks

cargo bench -p refeff-io --bench rdinp        # parser, CIF import, rdinp, potXX.dat
cargo bench -p refeff-core --bench core_tables # core numerical tables
cargo bench -p refeff-linalg --bench linalg    # linear-algebra bridge/solvers
cargo run -p xtask -- bench-e2e --example EXAFS/Cu --iterations 5 [--reference]

bench-e2e --reference additionally times the FEFF10 rdinp reference binary when it has been built. The refeff-io benchmark uses feff10/examples/EXAFS/Cu/feff.inp when the reference tree is present and falls back to a small embedded Cu input otherwise.

License

ReFEFF is a modified FEFF10 distribution and is distributed under the FEFF10 license. The license file contains the required modified-distribution marking; additional provenance is recorded in NOTICE.md. Redistribution must retain the notices, conditions, disclaimer, and marking required by that license.