Litmus

Litmus is an automated molecular integrals generator.

New to the codebase? Start with ONBOARDING.md for an architecture map, conventions, and pitfalls.

Building

Litmus uses CMake (>= 3.16) and a C++17 compiler. To build:

cmake -S . -B build              # configure (defaults to a Release build)
cmake --build build -j           # compile, produces build/litmus.x

To make a debug build instead, configure with cmake -S . -B build -DCMAKE_BUILD_TYPE=Debug.

Running

A run is described by a config file (a minimal TOML subset) and launched with the run subcommand:

./build/litmus.x run examples/t2c_geom.toml

The config selects the integral family (type), the maximum angular momentum (lmax), the operator label (integral), the geometric-derivative orders (geom), and a few family-specific keys. See litmus.x --help for the full schema and the ready-to-run samples under examples/. A minimal config looks like:

type     = "t2c_geom_cpu"   # run-type family
lmax     = 2                # maximum angular momentum
integral = "none"           # operator label
geom     = [0, 2, 0]        # geometric-derivative orders

Generated integral source files are written to the current working directory.

Testing

Unit tests use GoogleTest, fetched automatically at configure time (requires network access on the first configure). After building, run the suite with CTest:

ctest --test-dir build --output-on-failure

Tests live under tests/. Pass -DLITMUS_BUILD_TESTS=OFF at configure time to skip building them (e.g. for offline or packaging builds).