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About the developer

611 Stars 332 Forks GNU Lesser General Public License v3.0 15.6K Commits 243 Opened issues


Open-Source Quantum Chemistry – an electronic structure package in C++ driven by Python

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Contributors list

| Status | Azure DevOps builds Codecov coverage LGTM analysis LGTM analysis | | :------ | :------- | | Latest Release | Last release tag Commits since release python | | Communication | User site docs latest chat on forum dev chat on slack | | Foundation | license platforms python | | Installation | obtain latest Conda Anaconda-Server Badge | | Demo | Binder |

Psi4 is an open-source suite of ab initio quantum chemistry programs designed for efficient, high-accuracy simulations of molecular properties. We routinely perform computations with >2500 basis functions on multi-core machines.

With computationally demanding portions written in C++, exports of many C++ classes into Python via Pybind11, and a flexible Python driver, Psi4 strives to be friendly to both users and developers.

  • Users' Website

  • Downloading and Installing Psi4 (for the CMake adept, see CMakeLists.txt

  • Manual (built nightly from master branch) or (last release)

  • Tutorial for Psithon (

    ), for PsiAPI (
  • Forum

  • Communication & Support

  • GitHub (authoritative repository)

  • Continuous Integration Status Azure DevOps builds on Linux and Windows

  • Anaconda (binary available for Linux, Mac, Windows, and WSL Windows Binstar Badge ) instructions

  • Coverage Python and C++ source code lines hit by running most of the test suite. codecov

  • Interested Developers (replacement page needed) (welcome to fork psi4/psi4 and follow GitHub contribution procedure) PRs welcome

  • Sample Inputs (also in


  • Download Tarball

License license

Psi4: an open-source quantum chemistry software package

Copyright (c) 2007-2021 The Psi4 Developers.

The copyrights for code used from other parties are included in the corresponding files.

Psi4 is free software; you can redistribute it and/or modify it under the terms of the GNU Lesser General Public License as published by the Free Software Foundation, version 3.

Psi4 is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License for more details.

You should have received a copy of the GNU Lesser General Public License along with Psi4; if not, write to the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.

The full text of the GNU Lesser General Public License (version 3) is included in the COPYING.LESSER file of this repository, and can also be found here.

Citation doi

The journal article reference describing Psi4 is:

D. G. A. Smith, L. A. Burns, A. C. Simmonett, R. M. Parrish, M. C. Schieber, R. Galvelis, P. Kraus, H. Kruse, R. Di Remigio, A. Alenaizan, A. M. James, S. Lehtola, J. P. Misiewicz, M. Scheurer, R. A. Shaw, J. B. Schriber, Y. Xie, Z. L. Glick, D. A. Sirianni, J. S. O'Brien, J. M. Waldrop, A. Kumar, E. G. Hohenstein, B. P. Pritchard, B. R. Brooks, H. F. Schaefer III, A. Yu. Sokolov, K. Patkowski, A. E. DePrince III, U. Bozkaya, R. A. King, F. A. Evangelista, J. M. Turney, T. D. Crawford, C. D. Sherrill, "Psi4 1.4: Open-Source Software for High-Throughput Quantum Chemistry", J. Chem. Phys. 152(18) 184108 (2020).

  • doi for Psi4 v1.1
  • doi for Psi4NumPy
  • doi for Psi4 alpha releases
  • doi for Psi3

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