What is q2m3?¶

q2m3 is a Python framework for small-molecule QM/MM calculations. It combines PySCF chemistry with PennyLane quantum phase estimation (QPE) and sample-based quantum diagonalization (SQD). Fragment workflows apply the counterpoise correction to interaction energies from several electronic structure methods.

The project supports fixed point-charge embedding, Monte Carlo solvation, and quantum resource estimates. It does not include polarizable MM or an SQD-MC loop. The SQD implementation uses a classical simulator.

Start with Getting started and the H2 tutorials. Larger SQD calculations and Catalyst diagnostics can require more memory and compilation time.

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Project Links¶

Source repository: https://github.com/yjmaxpayne/q2m3
Issue tracker: https://github.com/yjmaxpayne/q2m3/issues
Zenodo archive (concept DOI): https://doi.org/10.5281/zenodo.20114945

Citation¶

Cite the Zenodo archive when you use q2m3 in research. The concept DOI identifies the project across releases. CITATION.cff lists the project citation and the concept DOI. The Zenodo record for each release lists its version DOI.

@software{q2m3_2026,
  title     = {q2m3: A Hybrid Quantum-Classical Framework for QM/MM Simulations},
  author    = {Ye Jun},
  year      = {2026},
  publisher = {Zenodo},
  doi       = {10.5281/zenodo.20114945},
  url       = {https://doi.org/10.5281/zenodo.20114945}
}