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/.
program |
Calculation types | Notes |
|---|---|---|
crest |
energy, gradient, hessian, optimization, conformer_search | GFN-xTB and GFN-FF built in |
dftbplus |
energy, gradient, hessian, optimization | DFTB3, SCC-DFTB, DFTB, and xTB; parameter-set settings from qcref |
geometric |
optimization, transition_state | Drives any gradient program (qccodec[geometric]) |
orca |
energy, gradient, hessian, optimization, transition_state | |
psi4 |
energy, gradient, hessian, optimization, transition_state | Any Psi4 method; point charges for QM/MM |
terachem |
energy, gradient, hessian, optimization | GPU quantum chemistry |
terachem-fe, terachem-pbs |
energy, gradient | TeraChem servers through tcpb (qccodec[tcpb]) |
xtb |
energy, gradient, hessian, optimization | GFN0/1/2-xTB, GFN-FF, g-xTB; point charges for QM/MM |
tblite |
energy, gradient | GFN1/GFN2/IPEA1-xTB as a Python library |
aimnet2 |
energy, gradient, hessian | AIMNet2 machine-learned potentials |
fairchem |
energy, gradient, hessian | UMA and eSEN (gated weights) |
mace |
energy, gradient, hessian | MACE-OFF, MACE-MP, MACE-OMOL, custom models |
orb |
energy, gradient | Orb v3 and OrbMol |
torchani |
energy, gradient, hessian | ANI-2x, ANI-1ccx, ... |
The last six run in the calling Python process: install the library next to qccompute (for example pip install tblite) instead of putting a program on PATH. Run any of them under geometric for optimizations and transition states.
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]. The tblite and machine-learned-potential codecs need their own libraries, installed separately (several of them, such as mace-torch and fairchem-core, cannot share an environment). Every library is imported only when a calculation is invoked.
1 maintainer
Metadata
1 maintainer
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