PSI4

Open-Source Quantum Chemistry

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About Us

We're Fast

PSI4 uses the latest techniques like density-fitting, and is optimized for multi-core execution of DFT, MP2, SAPT, and coupled-cluster.

We're Modular

PSI4 is a C++/Python core that easily interfaces with and is extended by standalone community projects in our growing Software Ecosystem.

We're Open Source

PSI4 is free and distributed under the truly open-source LGPL3 license. Use in education, research, and industry is encouraged.

We're Easy to Use

PSI4 uses simple input files and automates common procedures like basis set extrapolation and counterpoise correction.

We're Robust

PSI4 checks code changes with continuous integration and code coverage tools, and automatically keeps documentation up-to-date.

We're Developer-Friendly

PSI4 can be loaded as a Python module, so you can integrate it into your workflow. Plugins make it easy to extend features.

Get Started with Psi4

With computationally demanding portions in modern C++, exports of many classes into Python via Pybind11, and a flexible Python driver, PSI4 strives to be friendly to both users and developers.

Downloads Tutorials Programming
Meghna

Prof. Steven Wheeler, UGA

20 May 2016

The SAPT code is lightning fast and simple to use. The input file structure is also clean, simple, and intuitive.

Meghna

Mudong Feng

22 Feb 2019

After installing a new psi4conda with psi4 1.3rc2, threading issue is now solved. I can often get close to 1600% CPU usage and walltime of job is substantially reduced [from v1.1].

Latest Posts

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v1.3.1 — April 2019

Documentation Installers Source Release Notes Advertised Version: 1.3.1 Continuous Version: 1.3.1 Release Date: 15 April 2019 Documentation: http://psicode.org/psi4manual/1.3.1/ Availability: Public, GitHub source, CMake build, Conda binary installers Span: 5 + 4 partial PRs Enhancements #1570 (partial) better format exception when run_json encounters error. set_options can be used for local options, e.g., set_options({'scf__d_convergence': 8}). #1578 (1st commit) update schema name to qcschema_[in|out]put, use dtype=2 Molecule in schema, move psi4:qcvars to extras/qcvars.

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ACS Spring 2019 — Orlando

Psi4 developers and group members presented at the MolSSI Sustainable Software Symposium and several other symposia in the PHYS and COMP divisions. Some talks posted below. Roberto Di Remigio Reusable Components for Quantum Chemistry Software Lori Burns Composing and Decomposing Quantum Chemistry Software: Adventures with the Psi4 Ecosystem

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PS4Education Jupyter Labs Prerequisites

Some of the PSI4Education labs are presented as jupyter notebooks. Learn more about using jupyter notebooks here. The following Python scripting skills are assumed as prerequisite knowledge. Any other Python data structures or skills needed are explained within the lab. importing libraries assigning variables recasting data types slices and lists for loops logic statements print statements graphing data with matplotlib pyplot If you need tutorials on these Python skills, we recommend these lessons from the Molecular Sciences Software Institute.

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Psi4Education

Psi4Education: Computational Labs Using Free Software Computational chemistry is an increasingly important part of modern research, and yet it is often not part of the typical undergraduate or graduate curriculum. Fortunately, the availability of free software like PSI4 and WebMO lowers the barrier to introducing computational chemistry laboratory modules. The labs below were created using only free software and are available for use in your classes. Getting Started Installation and Setup Guide Instruction for installing WebMO and PSI4, along with information about creating and administering user accounts.

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v1.3 — February 2019

Documentation Installers Source Release Notes Advertised Version: 1.3 Continuous Version: 1.3 Release Date: 28 February 2019 Documentation: http://psicode.org/psi4manual/1.3/ Availability: Public, GitHub source, CMake build, Conda binary installers Span: 335 PRs, roughly 1065-1558 Major Points of Interest Added native Windows compatibility without the WSL requirement. DFT collocation grids can now be cache in-memory to avoid extra computation and lowering the total cost of DFT by up to a factor of two (#1233).

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Developers

Research Groups C. David Sherrill at Georgia Tech T. Daniel Crawford at Virginia Tech Ugur Bozkaya at Hacettepe University, Ankara, Turkey Fritz Schaefer at the University of Georgia Francesco Evangelista at Emory University Rollin A. King at Bethel University Eugene DePrince at Florida State University Official Author List Top GitHub Contributors 2018 Lori Burns at Georgia Tech Daniel G. A. Smith at MolSSI Raimondas Galvelis at Acellera, Spain Peter Kraus at Fritz Haber Institute, Germany Roberto Di Remigio at Arctic Univ.

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History

The Psi package originated in the group of Prof. Henry F. Schaefer while he was at the University of California, Berkeley. The code featured a direct CI code (written in 1976 by Robert Lucchese), a graphical unitary group configuration interaction (GUGA-CI) code (written in 1977-79 by Bernard Brooks and later extended to the shape-driven GUGA-CI code by Paul Saxe), and a Gaussian integral code (written in 1978 by Russell Pitzer).

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Software Publications

PSI4NUMPY: An Interactive Quantum Chemistry Programming Environment for Reference Implementations and Rapid Development J. Chem. Theory Comput. 14, 3504-3511 (2018) D. G. A. Smith, L. A. Burns, D. A. Sirianni, D. R. Nascimento, A. Kumar, A. M. James, J. B. Schriber, T. Zhang, B. Zhang, A. S. Abbott, E. J. Berquist, M. H. Lechner, L. A. Cunha, A. G. Heide, J. M. Waldrop, T. Y. Takeshita, A. Alenaizan, D.

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PsiCon 2018 — GaTech

Meeting Time and Location The meeting will be held from 10am on Friday, November 9, until noon on Saturday, November 10, in the Molecular Science and Engineering (MoSE) building at Georgia Tech. Nearby hotels, and local travel information, is available here. We are planning on providing coffee and a light breakfast on Friday and Saturday mornings, and lunch on Friday afternoon. Participants are requested to register so that we can get a headcount for planning purposes.

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v1.2 — July 2018

Documentation Installers Source Release Notes Advertised Version: 1.2 Continuous Version: 1.2 Release Date: 4 July 2018 Documentation: http://psicode.org/psi4manual/1.2/ Availability: Public, GitHub source, CMake build, Conda binary installers Major Points of Interest The DFT kernels were migrated to use LibXC, Psi4 now has 400+ functionals including modern functionals such as wB97M-V. The DFT code was optimized leading up to a 4x speed enhancement on 6 cores. A new Density-Fitted JK backend was written, DF-SCF is now up to 2x as fast.

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WWDC 2017 — Virginia Tech

Meeting Time and Location The meeting was held from Friday, November 3, until noon on Saturday, November 4, at the Hyatt Place hotel in Blacksburg, Virginia, featuring participants from 7 institutions. Participating Institutions Virginia Tech Emory University of Georgia Georgia Tech NIH Bethel University OpenEye Agenda Friday, November 4 9:00-9:10am - Welcome (Daniel Crawford, VT) 9:10-9:40am - Psi4 Ecosystem Developments in 2017 (Lori Burns, GT) 9:40-9:55am - Industrializing Psi4 Non-Covalent Calculations with Applications to Crystal Packing (Tom Darden, OpenEye) 9:55-10:10am - New Features and Ongoing Developments in Forte (Francesco Evangelista, Emory) 10:10-10:30am - Coffee Break 10:30-11:10am - Psi4’s DFT and SAPT(DFT) Design Architecture: Successes, Failures, and Lessons (Daniel Smith, MolSSI) 11:10-11:25am - PyOptking: A New Geometry Optimizer for Psi4 (Rollin King, Bethel) 11:25-11:40am - Upcoming Infrastructure and API Changes in Conventional Coupled-Cluster (Andrew James, VT) 11:40-11:55am - A C++ Toolchain to Aid Debugging (Justin Turney, UGA) 12:00-1:00pm - Lunch 1:00-2:00pm - Psi4 SWOT Analysis and Strategic Planning 2:00-3:30pm - Break 3:30-5:30pm - Breakout Strategy Sessions 6:00pm - Dinner Saturday, November 4 9:00-10:30am - Reports from Breakout Groups 10:30-11:00am - Coffee Break 11:00am-12:30pm - Lightning Talks

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v1.1 — May 2017

Documentation Installers Source Release Notes Advertised Version: 1.1 Continuous Version: 1.1 Release Date: 19 May 2017 Documentation: http://psicode.org/psi4manual/1.1/ Availability: Public, GitHub source, CMake build, Conda binary installers New Methods Added analytic RHF Hessians, conventional and density fitted. Added analytic RHF CCSD(T) gradients (no frozen core). Added functional-group and intramolecular symmetry-adapted perturbation theory (F/I-SAPT) capabilities, scripts, and tests. (DOIs: 10.1021/ct500724p, 10.1063⁄1.4927575) Added high-spin open-shell SAPT0. Note that Ind20,r (and exch counterpart) contains unrelaxed induction.

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Developers' Conference 2016 — UGA

PSI4 Developers’ Conference Nov 2016 Meeting Summary The meeting was held Friday and Saturday, Nov 4-5, at CCQC at UGA featuring participants from 9 institutions. Emory University University of Georgia Virginia Tech Georgia Tech Florida State University Auburn University NIH Bethel OpenEye Agenda Friday, Nov 4 9:30am-10:00am: Coffee and Social 9:50am-10:00am: Welcome 10:00am-11:00am: Session 1 David Sherrill: Impact of the Psi4 Project Daniel G. A. Smith: Psi4: Benefits of Becoming a Library Andrew James: Making LibDPD Great Again 11:00am-11:15am: Coffee Break 11:15am-12:00pm: Session 2 Andrew Simmonett, Lori Burns, Justin Turney: Psi4 Then and Now Ryan Richard: Pulsar 12:00pm-1:30pm: Lunch provided by Dell - “Lunch and Learn” 11:15am-12:00pm: Session 3 Daniel Crawford: Software Institute Kevin Hannon: Parallel MCSCF Mike Zott: Psi4 and OpenMM 1:30pm-1:45pm: Lori Burns: Psi Licensing 1:45pm-2:00pm: David Sherrill: Psi Management Structure 2:45pm-3:00pm: Coffee Break 3:00pm-5:00pm: Breakout Sessions Ask an Expert Documentation Challenge Feature Requests Saturday, Nov 5

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v1.0 — July 2016

Documentation Installers Source Release Notes Advertised Version: 1.0 Continuous Version: 1.0 Release Date: 4 Jul 2016 Documentation: http://psicode.org/psi4manual/1.0.0/ Availability: Public, GitHub source, CMake build, Conda binary installers Psi4 1.0 Release Notes Psi4 is, in many ways, a whole new package compared to Psi3. While some libraries and modules remain the same, the majority of the code has been rewritten from scratch based on a powerful set of new libraries written in C++.

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Developers' Conference 2015 — Emory

Meeting Summary The meeting was held Friday and Saturday, Nov 13-14, at Emory featuring participants from 7 institutions. 36 people attended in person at Emory. The following are outcomes of the meeting: The Ambit library seems to be working well for shared-memory systems. We will attempt to adopt Ambit for tensors in shared-memory and distributed-memory environments. We will aim to adopt Lightspeed when it becomes available. The Lightspeed classes can serve as a template for communications between modules in Psi4.

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Developers' Conference 2014 — GaTech

Meeting Time and Location The meeting was held from Friday, November 14, until Saturday, November 15 at Georgia Tech. Participating Institutions Georgia Tech Virginia Tech University of Georgia Emory University Chemical Semantics, Inc ETH, Zurich Auburn University NIH Florida State University Ataturk University, Turkey University of Tromso, Norway University of Memphis Agenda Friday, November 14 MoSE 4202A 10:00am-10:10am: Welcome and Introductions 10:10am-10:25am: David Sherrill: Response of the Community to Psi4 10:25am-11:15am: Updates from developers: Daniel Crawford: PCMSolver and potential infrastructure changes (10 mins) Ugur Bozkaya: DF-GRAD (5 mins) Rollin King: Optimizer improvements, XML output (15 min) (Summary of Optking changes) Bing Wang and Neil Ostlund: Enriching Psi4 Data with the Semantic Web (20 min) 11:15am-11:30am: Coffee Break 11:30am-12:00pm: Updates from developers: Justin Turney: Density Cumulant and Transcorrelated Methods (15 min) Daniel Smith: MCSCF and psi4numpy (10 min) Lubos Horny: Parity violation code (5 min) 12:00pm- 1:00pm: Lunch (provided) 1:00pm-2:00pm: Updates from developers: Ryan Richard: Parallelization, Many-body expansion, GTFock interface to Psi4 (15 min) Ben Pritchard: PANACHE update (5 min) Francesco Evangelista: Scalar relativistic methods (15 min) Lori Burns: Common Driver, Databases, and Basis Sets (10 min) Rob Parrish: A-SAPT, F-SAPT, I-SAPT (10 min) Jerome Gonthier: Open-shell SAPT (5 min) 2:00pm-2:15pm: Break 2:15pm-3:15pm: Breakout Session I: Data archiving and interchange: Export to XML, CML, CSX, etc.

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Beta5 — July 2013

Documentation Source Release Notes RN at GitHub link much better formatted than below. Advertised Version: 4.0b5 Continuous Version: 1.0b5 Release Date: 3 Jul 2013 Documentation: http://psicode.org/psi4manual/4.0b5/ Availability: Public, Sourceforge source, Autotools build, No binary This release adds a little additional functionality, fixes several bugs, improves the installation process and the documentation, and adds a couple of new built-in databases. It also includes some work-in-progress that will lead to improvements in the next release.

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Beta4 — Apr 2013

Documentataion Source Release Notes Advertised Version: 4.0b4 Continuous Version: 1.0b4 Release Date: 7 Apr 2013 Documentation: http://psicode.org/psi4manual/4.0b4/ Availability: Public, Sourceforge source, Autotools build, No binary The first public beta release includes all-new, very efficient density-fitted, shared-memory parallel code for Hartree-Fock, DFT, and MP2, and symmetry-adapted perturbation theory (SAPT). We also add new code for MP4, QCISD(T), and G2. New modules performing frozen natural orbital coupled-cluster have been added. Previous PSI3 functionality for coupled-cluster energies and properties, and arbitrary-order CI and MBPT energies is also available.

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Beta3 — Oct 2012

Documentation Source Release Notes Advertised Version: 4.0b3 Continuous Version: 1.0b3 Release Date: 23 Oct 2012 Documentation: http://psicode.org/psi4manual/4.0b3/ Availability: Private, No Sourceforge source, Autotools build, No binary This version of PSI contains the following features: Hartree-Fock, DFT, MP2, CI, CC, PSIMRCC, ADC(2), SAPT, DCFT, and optimized-orbital MP2 and MP3. Density-fitting is available for Hartree-Fock, DFT, MP2, and SAPT, and is much faster than the conventional algorithms. Most popular functionals are available, but only M05 and M05-2X are available among meta-GGA’s.

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Beta2 — May 2012

Documentation Source Release Notes Advertised Version: 4.0b2 Continuous Version: 1.0b2 Release Date: 6 May 2012 Documentation: http://psicode.org/psi4manual/4.0b2/ Availability: Private, No Sourceforge source, Autotools build, No binary The Beta2 release fixes the following bugs reported by beta testers: * Boost library compilation inside PSI4 now uses the user’s PYTHON environmental variable, to help avoid the situation where one version of Python is used for Boost, and another for PSI4, leading to linker errors.

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Beta1 — Feb 2012

Source Release Notes Advertised Version: 4.0b1 Continuous Version: 1.0b1 Release Date: 2 Feb 2012 Documentation: None Availability: Private, No Sourceforge source, Autotools build, No binary

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