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As of July, 2015, we are making available Linux binaries for the nightly development build of Psi4. This is recommended for most users, as these builds are normally (but not always) stable and contain the lastest improvements and bugfixes. Presently, the stable builds are considerably older.

Download options:

  • Nightly build binary (Linux only)
  • Latest source tarball from github
  • Clone psi4public repository from github
  • Last stable source tarball from sourceforge
  • A more complete list of possible ways to get Psi4 and a comparison between them is provided here

    Changes Since Last Stable Release

  • Created binary distribution of Psi4 for users
  • New cmake build system for developers
  • [in progress] Added Ability to call CFOUR from Psi4
  • [in progress] Added EFP energies added via libEFP
  • [in progress] Added PCM implicit solvent added for SCF
  • [in progress] Added quadratically convergent SCF algorithm for DF-RHF and DF-UHF
  • [in progress] Added RASSCF and CASSCF energies
  • [in progress] Added X2C scalar relativistic corrections
  • [in progress] Added DF-CCSD gradients (RHF references)
  • [in progress] Improvements to the reporting of SAPT summary information, and enhancements to obtain SAPT methods reported in doi: 10.1063/1.4867135.
  • QM/MM computations with MM point charges: energies and gradients
  • Fixed a bug with DF-K in systems with only one occupied orbital
  • Fixed an integer overflow bug in DF-CCSD(T)
  • Added automatic defaults for auxiliary basis sets
  • More sophisticated user input for one-electron property analysis of coupled-cluster wavefunctions
  • Added UHF/UHF stability analysis for non-PK integrals
  • Added density cumulant functional theory methods DC-12, ODC-12, and ODC-13
  • Improvements to geometry optimizer
  • Added interface to DMRG-CI and DMRG-SCF code in CheMPS2
  • Added UHF DF-MP2 gradients and DF-MP3 energies
  • Added MP2.5 and MP3 energies and gradients and orbital-optimized versions of the same
  • Added CCD treatment of dispersion in SAPT
  • Added DF orbital-optimized MP2.5 energies and gradients
  • Added code to output cube files for orbitals, densities, etc.
  • Added GUESS_MIX keyword to UHF/UKS to generate broken-symmetry guesses
  • More user-friendly error checking: If the user specifies an unknown keyword, the program will print that this keyword is unknown and will suggest possible alternatives that are close in spelling
  • Added command-line arguments -l to specify PSIDATADIR (for developers) and -s to specify location of scratch directories (overrides PSI_SCRATCH)
  • Added STO-3G, 3-21G, and def2 basis sets through radon
  • Added code to do potential energy scans via the WebMO interface
  • Fixed crash caused by changing number of MO's during optimization (changes in number of MO's dropped due to linear dependencies)
  • Sped up integrals computation by optimizing libmints layer
  • Added Cholesky-decomposition MP2 and optimized-orbital MP2
  • Fixed modules that crashed when not finding full integral files available (because DF-HF was run instead of conventional HF)
  • Fixed problem with double hybrid DFT total energies not being printed
  • Internal upgrades to the direct product decomposition library, libdpd, especially regarding density fitting
  • Updates to MOLDEN writer
  • Various other bugfixes
  • Beta5 Release Notes

    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.

    The Beta5 release (7/3/2013; User's Manual) includes the latest accomplishments:

    • WARNING: Double hybrids like B2PLYP are not having their total energies printed to the output file. This is fixed in future versions. In Beta5 you can simply work around this problem by saving the total energy in a variable and printing it, like this: etot = energy('b2plyp'), print etot
    • WARNING: There has been a name change in the PSI4 Python driver to replace PsiMod with psi4. This change will prevent PSI4 from running if you have any reference to PsiMod in your input files or in a .psi4rc file. If you get any error complaining about one of those words, immediately check your .psi4rc or .psirc files and rename any PsiMod to psi4.
    • Standardize psi variable naming for mp2 modules
    • Add capability to compute frequencies by finite difference of energies in embarrasingly parallel fashion
    • Fix problem in database wrapper where named subsets (other than small/large) wouldn't run
    • Fix problem with computing multiplicity in database with fragmented open-shell molecules
    • Allow more complex model chemistries through cbs() wrapper. Add alias for Wes Allen's focal point analysis
    • Alias sherrillgroup_gold_standard renamed to sherrill_gold_standard
    • Make cbs() wrapper work with MRCC interface
    • CC code can now be used to compute energies with applied external field. Charges must be set up using the QM/MM module.
    • DF-CC code now uses two sets of 3-index integrals: one for building the Fock matrix and one for all other ERI's
    • Implementation of libefp is in progress
    • Improved documentation of CC codes
    • Improved handling of certain out-of-core contractions in CC code
    • Added HTR40 database of hydrogen transfer reactions
    • Partial fix to fallback to non-DF SCF when DF basis not available
    • Allows PSI4 to be run interactively
    • Updated naming of external files such as MOLDEN files
    • Initial work to make PSI4 work with cmake
    • Some changes to make more compatible with C++11
    • Allow user-specified fixed geometry coordinates

    Beta4 Release Notes

    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. A completely new, very user-friendly input format has been implemented, and it can be (optionally) mixed with Python to allow automation of very complex tasks with simple input files. Built-in routines to handle counterpoise correction and basis set extrapolation are included.

    The Beta4 release (4/7/2013; User's Manual) is the first public version. The latest accomplishments are:

    • Frozen Natural orbital CCSD(T) code available
    • RHF MP4, QCISD(T), and G2 features added
    • dlDF-D available
    • Interface to WebMO completed
    • General framework for double-hybrid functionals, with several added such as B2PLYP
    • More efficient Density Cumulant Functional Theory (DCFT) code with analytic gradients working
    • Production-level DFT code implemented for GGA, LRC, and Meta functionals.
    • 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 Kallay's MRCC code
    • Interface to PubChem to allow chemical names in lieu of coordinates in molecule inputs

    Beta3 Release Notes

    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. DFT gradients have not been tested extensively yet. We recommend linking to a threaded BLAS library and running with multiple threads. Intel's MKL library works particularly well in this regard.

    The Beta3 release (10/23/2012; User's Manual) contains many enhancements and bug fixes. Among them are:

    • More appropriate default values for convergence criteria and grids should speed up computations
    • Density-fitting is now turned on by default when it is available, resulting in much, much faster computations
    • dlDF+D and support for double-hybrids now available
    • Utilizes Grimme's DFTD3 program if present to enable -D3 corrections
    • Fixes a problem with optimizations using Z-matrices
    • Use analytic gradients by default when they are available

    Beta2 Release Notes

    The Beta2 release (5/6/2012; User's Manual) 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.
    • Problems were encountered when compiling with versions of OpenMP older than version 3. Code specific to OpenMP 3 has been removed. The code should now compile with OpenMP 2.
    • User manual has been updated to remove mention of dependency script, which was only intended for machines that had very few of the relevant dependencies installed (unusual case).