Psi is an
ab initio
''Ab initio'' ( ) is a Latin term meaning "from the beginning" and is derived from the Latin ''ab'' ("from") + ''initio'', ablative singular of ''initium'' ("beginning").
Etymology
Circa 1600, from Latin, literally "from the beginning", from ab ...
computational chemistry package originally written by the research group of
Henry F. Schaefer, III (
University of Georgia
, mottoeng = "To teach, to serve, and to inquire into the nature of things.""To serve" was later added to the motto without changing the seal; the Latin motto directly translates as "To teach and to inquire into the nature of things."
, establ ...
). Utilizing Psi, one can perform a calculation on a
molecular system with various kinds of methods such as
Hartree-Fock,
Post-Hartree–Fock
In computational chemistry, post-Hartree–Fock methods are the set of methods developed to improve on the Hartree–Fock (HF), or self-consistent field (SCF) method. They add electron correlation which is a more accurate way of including the repu ...
electron correlation methods, and
Density functional theory
Density-functional theory (DFT) is a computational quantum mechanical modelling method used in physics, chemistry and materials science to investigate the electronic structure (or nuclear structure) (principally the ground state) of many-body ...
.
The program can compute energies, optimize molecular geometries, and compute vibrational frequencies.
The major part of the program is written in
C++
C++ (pronounced "C plus plus") is a high-level general-purpose programming language created by Danish computer scientist Bjarne Stroustrup as an extension of the C programming language, or "C with Classes". The language has expanded significan ...
, while
Python
Python may refer to:
Snakes
* Pythonidae, a family of nonvenomous snakes found in Africa, Asia, and Australia
** ''Python'' (genus), a genus of Pythonidae found in Africa and Asia
* Python (mythology), a mythical serpent
Computing
* Python (pro ...
API
An application programming interface (API) is a way for two or more computer programs to communicate with each other. It is a type of software interface, offering a service to other pieces of software. A document or standard that describes how ...
is also available, which allows users to perform complex computations or automate tasks easily.
Psi4 is the latest release of the program package - it is
open source, released as
free under the
GPL
The GNU General Public License (GNU GPL or simply GPL) is a series of widely used free software licenses that guarantee end users the four freedoms to run, study, share, and modify the software. The license was the first copyleft for general u ...
through
GitHub
GitHub, Inc. () is an Internet hosting service for software development and version control using Git. It provides the distributed version control of Git plus access control, bug tracking, software feature requests, task management, continu ...
. Primary development of Psi4 is currently performed by the research groups of
David Sherrill (
Georgia Tech
The Georgia Institute of Technology, commonly referred to as Georgia Tech or, in the state of Georgia, as Tech or The Institute, is a public research university and institute of technology in Atlanta, Georgia. Established in 1885, it is part of ...
), T. Daniel Crawford (
Virginia Tech
Virginia Tech (formally the Virginia Polytechnic Institute and State University and informally VT, or VPI) is a public land-grant research university with its main campus in Blacksburg, Virginia. It also has educational facilities in six re ...
), Francesco Evangelista (
Emory University
Emory University is a private research university in Atlanta, Georgia. Founded in 1836 as "Emory College" by the Methodist Episcopal Church and named in honor of Methodist bishop John Emory, Emory is the second-oldest private institution of ...
), and
Henry F. Schaefer, III (
University of Georgia
, mottoeng = "To teach, to serve, and to inquire into the nature of things.""To serve" was later added to the motto without changing the seal; the Latin motto directly translates as "To teach and to inquire into the nature of things."
, establ ...
), with substantial contributions by Justin Turney (
University of Georgia
, mottoeng = "To teach, to serve, and to inquire into the nature of things.""To serve" was later added to the motto without changing the seal; the Latin motto directly translates as "To teach and to inquire into the nature of things."
, establ ...
), Andy Simmonett (
NIH
The National Institutes of Health, commonly referred to as NIH (with each letter pronounced individually), is the primary agency of the United States government responsible for biomedical and public health research. It was founded in the late ...
), and Rollin King (
Bethel University).
Psi4 is available on Linux releases such as Fedora and Ubuntu.
Features
The basic capabilities of Psi are concentrated around the following methods
of
quantum chemistry:
*
Hartree–Fock method
In computational physics and chemistry, the Hartree–Fock (HF) method is a method of approximation for the determination of the wave function and the energy of a quantum many-body system in a stationary state.
The Hartree–Fock method often ...
*
Density functional theory
Density-functional theory (DFT) is a computational quantum mechanical modelling method used in physics, chemistry and materials science to investigate the electronic structure (or nuclear structure) (principally the ground state) of many-body ...
*
Møller–Plesset perturbation theory
Møller–Plesset perturbation theory (MP) is one of several quantum chemistry post–Hartree–Fock ab initio methods in the field of computational chemistry. It improves on the Hartree–Fock method by adding electron correlation effects by ...
*
Coupled cluster
Coupled cluster (CC) is a numerical technique used for describing many-body systems. Its most common use is as one of several post-Hartree–Fock ab initio quantum chemistry methods in the field of computational chemistry, but it is also used in ...
*
CASSCF
*
multireference configuration interaction In quantum chemistry, the multireference configuration interaction (MRCI) method consists of a configuration interaction expansion of the eigenstates of the electronic molecular Hamiltonian in a set of Slater determinants which correspond to excita ...
methods
*
symmetry-adapted perturbation theory
Several methods are available for computing excited electronic states, including
configuration interaction singles (CIS), the
random phase approximation The random phase approximation (RPA) is an approximation method in condensed matter physics and in nuclear physics. It was first introduced by David Bohm and David Pines as an important result in a series of seminal papers of 1952 and 1953. For deca ...
(RPA),
time-dependent density functional theory (TD-DFT), and equation-of-motion coupled cluster (EOM-CCSD).
Psi4 has introduced the density-fitting approximation in many portions of the code, leading to faster computations and reduced I/O requirements.
Psi4 is the preferred quantum chemistry backend for the OpenFermion project, which seeks to perform quantum chemistry computations on quantum computers.
In Psi4 1.4,
the program was adapted to facilitate high-throughput workflows and can be connected t
BrianQCto speed up calculations for
Hartere-Fock and
Density functional theory
Density-functional theory (DFT) is a computational quantum mechanical modelling method used in physics, chemistry and materials science to investigate the electronic structure (or nuclear structure) (principally the ground state) of many-body ...
methods.
See also
*
List of quantum chemistry and solid-state physics software
Quantum chemistry computer programs are used in computational chemistry to implement the methods of quantum chemistry. Most include the Hartree–Fock (HF) and some post-Hartree–Fock methods. They may also include density functional theory (DFT) ...
References
External links
Psi4 HomepagePsi4 Source Code (GitHub)
{{DEFAULTSORT:Psi (Computational Chemistry)
Computational chemistry software
Free chemistry software
Chemistry software for Linux