psi4/psi4

Health v2 · maintenance only

Adoption not part of the score

1215 stars · 510 forks observed · 2026-08-28

What it is AI-extracted, prompt v1, taxonomy v1, 2026-08-30, confidence not recorded

Psi4 is an open-source quantum chemistry package for electronic structure calculations, with computationally demanding code in C++ and a flexible Python driver. It supports methods from Hartree-Fock and DFT to coupled cluster, SAPT, and multireference theory, usable both as an executable and as a Python module.

Use cases

• compute molecular energies and geometries with DFT or coupled cluster
• run quantum chemistry calculations from Python scripts
• perform symmetry-adapted perturbation theory (SAPT) on molecular complexes
• optimize molecular geometries and compute vibrational frequencies
• teach computational chemistry in university labs
• calculate intermolecular interaction energies with counterpoise correction

When to choose

• you need a free, open-source electronic structure package with modern methods like DLPNO-CCSD(T) and F12
• you want to script quantum chemistry workflows via a Python API or QCSchema
• you need fast multicore execution of DFT, MP2, SAPT, or coupled-cluster calculations
• you want an extensible platform that integrates with the QCArchive ecosystem

When to avoid

• you need a graphical molecular builder or visualization frontend
• you require methods outside Psi4's supported set or highly specialized proprietary codes
• you want a lightweight tool for quick back-of-the-envelope chemistry without HPC resources

Facets

application · maturity active

simulation sdk cli developer-tools chemistry data-science education windows python cpp cli quantum-chemistry electronic-structure computational-chemistry dft coupled-cluster sapt molecular-modeling scientific-computing physics linux macos

Member repositories

For agents

markdown · JSON · MCP: product_card(name="psi4/psi4")