• Users' Website: www.psicode.org
• Download Tarball: http://sourceforge.net/projects/psicode/ (NSF likes to see download tallies which GitHub doesn't provide)
• Developers' GitHub Wiki: https://github.com/psi4/psi4/wiki (currently private, transition soon)
• Manual: http://sirius.chem.vt.edu/psi4manual/master/index.html (built nightly from master branch)

PSI4 is an open-source suite of ab initio quantum chemistry programs designed for efficient, high-accuracy simulations of a variety of molecular properties. We can routinely perform computations with more than 2500 basis functions running serially or with modest parallelism.

With computationally demanding portions written in C++, Boost exports of many C++ classes into Python, and a flexible Python driver, PSI4 strives to be friendly to both users and developers.

[22 Jan 2014] Renamed psi4release to psi4public, since master branch is continuously synced with private master branch, rather than reflecting static stable releases. Interested developers are welcome to fork this repository -OR- clone and store branches here at psi4/psi4public (those with collaborator access) -OR- clone and store private branches at psi4/psi4 (those with collaborator access to the private repo). A new stable, fully tested beta6 should appear within a few weeks. Youtube links to psi4 developer training should appear after our workshop this Friday.

[11 Nov 2013] We are transitioning from main development on a private GitHub repository toward main development on this public repository. Sensitive code (prone to scientific scooping) will remain on the private branch, but otherwise we anticipate that contributions from both the primary developers and any interested persons shall be made here. As of today, the public and private repos are synced, but this isn't necessarily the most stable version. A new stable, fully tested beta6 should appear before the end of the year.