qccodec

Translates qcdata inputs into native program inputs and parses program outputs back into qcdata objects, one codec per program.

Documentation, including a copy-and-paste example script for every program and calculation type: qccodec.docs.atomsforhumanity.org

The QC Suite

These packages work together to make quantum chemistry fast, structured, and interoperable.

• qcref - Reference data for computational chemistry: CODATA physical constants, conversion factors, a periodic table, and solvent properties, each value with its source.
• qcdata - Data structures for quantum chemistry inputs and results, with Jupyter visualizations. Documentation
• qcinf - Cheminformatics algorithms and structure utilities for qcdata structures.
• qccodec - Translates qcdata inputs into native program inputs and parses program outputs back into qcdata objects, one codec per program. Documentation
• qccompute - Runs quantum chemistry programs on qcdata inputs using qccodec codecs and returns structured results. Documentation
• BigChem - Distributed execution of qccompute calculations across clusters of computers or the cloud.
• ChemCloud - A web application and Python client that expose a BigChem cluster securely over the internet.

✨ Basic Usage

qccodec never runs programs itself; qccompute runs them and uses qccodec on both ends.

python -m pip install qccompute   # also installs qccodec

from qcdata import CalcType, Model, ProgramInput, Structure
from qccompute import compute

prog_input = ProgramInput(
    program="psi4",
    calctype=CalcType.gradient,
    structure=Structure(
        symbols=["O", "H", "H"],
        geometry=[[0.0, 0.0, 0.0], [0.524, 1.687, 0.48], [1.146, -0.45, -1.354]],
    ),
    model=Model(method="wb97x-d", basis="def2-svp"),
    keywords={"d_convergence": 1e-8},  # Psi4's own option names
)
output = compute(prog_input)
print(output.results.energy, output.results.gradient)

Decode output you already have, from Python or the command line:

from pathlib import Path
from qccodec import decode

data = decode("terachem", "hessian", stdout=Path("tc.out").read_text())
data.energy, data.hessian, data.freqs_wavenumber

qccodec terachem hessian tc.out > data.json

See Decoding program output for directories, failed calculations, and encoding without running.

Supported programs

Each program has a documentation page and a runnable example script for every calculation type in examples/.

To support a new program, see Writing a codec and the step-by-step walkthrough in CONTRIBUTING.md.

Contributing

See CONTRIBUTING.md for development setup, the pre-commit workflow, running tests, and the release process.

If there's data you'd like parsed from output files or a program you'd like supported, open an issue describing the data and include an example output file, like this.

Optional dependencies

Optional integrations install with qccodec[geometric] or qccodec[tcpb]; their libraries are imported only when a calculation is invoked.