Psi4 is a quantum chemistry package for performing high-accuracy electronic-structure calculations on molecules. It combines a computational core written in C++ with a Python interface, offering both efficient numerical algorithms and flexible control over scientific workflows.
The software is intended for researchers studying molecular energies, electronic properties, chemical bonding and intermolecular interactions. It supports a wide range of theoretical approaches, from relatively inexpensive density-functional calculations to sophisticated electron-correlation methods.
Python plays an important role in Psi4’s design. Researchers can perform routine calculations with straightforward input files or use the Python API to construct more elaborate procedures, automate repeated calculations and integrate electronic-structure methods into larger scientific applications.
Psi4 also makes extensive use of density fitting and multicore parallelism to improve computational performance.
This is free and open source software.
Key Features
- Supports restricted, unrestricted and restricted open-shell Hartree-Fock calculations.
- Provides density-functional theory with a wide range of exchange-correlation functionals.
- Includes second-order Møller-Plesset perturbation theory and orbital-optimised methods.
- Supports coupled-cluster calculations including CCSD and CCSD(T).
- Provides symmetry-adapted perturbation theory for analysing intermolecular interactions.
- Includes configuration interaction and density cumulant functional theory methods.
- Supports excited-state calculations using EOM-CC and algebraic diagrammatic construction methods.
- Calculates molecular geometries, vibrational frequencies and thermochemical properties.
- Provides analytical gradients and Hessians for supported methods.
- Supports counterpoise corrections and basis-set extrapolation workflows.
- Calculates electronic properties including dipole moments and polarizabilities.
- Offers a Python API for scripting, workflow automation and integration with other scientific tools.
- Supports plugins and integrations with external computational chemistry packages.
- Cross-platform support – runs on Linux, macOS, and Windows.
Website: www.psicode.org
Support:
Developer: The Psi4 Developers
License: GNU Lesser General Public License v3.0
Psi4 is written in C++ and Python. Learn C++ with our recommended free books and free tutorials. Learn Python with our recommended free books and free tutorials.
Related Software
| Quantum Chemistry & Electronic Structure | |
|---|---|
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| pyscf | Python framework for electronic structure calculations |
| Quantum ESPRESSO | Plane-wave DFT calculations for electronic structure and materials |
| OpenMolcas | Advanced multiconfigurational methods for molecular chemistry |
| MPQC | Massively parallel electronic structure calculations for research |
| GPAW | Density functional theory calculations using the PAW method |
| DFTB+ | Fast atomistic modelling using density-functional tight binding |
| MOPAC | Semiempirical quantum chemistry for molecules and materials |
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