Last modified 17 months ago Last modified on 01/24/14 11:01:58

Welcome to the PSI4 Trac Page

The PSI4 Project aims to provide very efficient code for quantum chemistry, using the latest techniques such as density fitting, Cholesky decomposition, and Laplace energy denominators. The code will be open-source and given away for free, to maximize its impact in science and engineering. We are adding shared-memory and distributed-memory parallel algorithms, and some parts of the code are being adapted to utilize graphical processing units (GPUs).

This is the website for PSI4 developers. If you want to become a PSI4 developer, please contact Professors Daniel Crawford or David Sherrill.

Users should go to the following site:

Developers: We have moved development to GitHub. Please sign up for a free account at and contact one of the lead developers for access.

We had an initial beta release of the code in spring 2012. A more mature version, Beta3, became available for testing in October 2012. The Beta3 pre-release is now available to collaborators and a limited number of beta-testers.

PSI4 News

  • Programmers' Workship at Georgia Tech, January 24, 2014
  • PSI Workshop at Georgia Tech, March 9-10, 2012
  • The Beta3 Release is completed and will be provided to a limited number of beta testers.
  • Progress towards "Release Candidate 1" milestone: 55%.
  • A preview of the PSI4 code and its capabilities has been published online in Wiley Interdisciplinary Reviews: Computational Molecular Science (DOI: 10.1002/wcms.93)
  • Our very fast SAPT0 code for analysis of intermolecular interactions has been published in a paper in the Journal of Chemical Physics (DOI: 10.1063/1.3656681)
  • The SVN repository is gone. Refer to GitObtaining for instructions on obtaining PSI4

Latest Accomplishments

  • Electrostatic potentials and general-order multipoles added
  • PSI4/WebMO interface completed
  • Double-Hybrid Density Functionals enabled
  • More efficient Density Cumulant Functional Theory (DCFT) code with analytic gradients working
  • Production-level DFT code implemented for GGA, LRC, and Meta functionals. TDDFT coming soon!
  • Production-level DF-MP2 code working with RHF, UHF, ROHF references
  • ADC(2) propagator code working
  • CC gradients, CC response, CI energies, MP(n) energies, ZAPT(n) energies, EOM-CC excitation energies, CC3 energies working
  • Extremely efficient, threaded SAPT code completed
  • User-friendly interface to Kállay's MRCC code
  • Interface to PubChem to allow chemical names in lieu of coordinates in molecule inputs

Latest Plans

  • GPU coupled-cluster code
  • Large-scale CIS code
  • Finish bringing over the rest of the PSI3 capabilities

PSI4 Source Code

  • GitObtaining -- Checking out the code from the Git repository
  • GitPull -- Obtaining new changes from the repository
  • GitBranches -- Managing local branches and their interaction with the repository
  • GitPush -- Checking in your changes to the repository
  • GitTutorial -- A short Git Tutorial
  • GitTarball -- Creating a tarball file from a branch
  • GitTrouble -- Error you might encounter and how to resolve them

Compiling PSI4

Running PSI4

Information About Existing Modules

  • SCF -- The SCF solver module
  • OPTKING -- The OPTKING geometry optimization routines

Information About Existing Libraries

Making New PSI4 Modules

  • NewModules -- A guide to adding new features to PSI4, and creating plugins
  • PythonAndPsi -- Integrating your module with PSI4 and Python
  • TestCases -- The PSI4 test suite
  • SphinxDocs -- Documenting PSI4 with Sphinx

Useful Documents

Help with Trac

For a complete list of local wiki pages, see TitleIndex.