• Advertised Version: 1.4
• Continuous Version: 1.4
• Release Date: 3 August 2021
• Documentation: https://psicode.org/psi4manual/1.4.0/
• Availability: Public, GitHub source, CMake build, Conda binary installers
• Span: 437 PRs, roughly 1559-2264

Obtaining

• Binary installers: see link above
• Python Anaconda: conda install psi4 -c psi4.
• Windows conda packages available (#1560)
• Dropped dependencies: deepdiff, Libint1
• Added dependencies: QCEngine, Libint2

New Methods

• Add ability to call Axilrod-Teller-Muto (ATM) 3-body dispersion correction from Grimme’s DFTD3. Note that this is for dftd3 call, not energy call (#1491)
• MP2D energies and gradients with help of external program (#1661)
• SCAN functionals – SCAN0, revSCAN0, SCAN, revSCAN, BMK, revM06-L (#1597)
• hybrid LDA functionals – CAM-LDA0, LDA0 (when Libxc puts them in a release) (#1645)
• FISAPT-D (#1670)
• Superposition of atomic potentials (SAP) guess (#1665, #1700)
• Implementation of partial Cholesky orthogonalization (#1760, #1817, #1824 #1842)
• Overlap half-derivative integrals (#1895)
• TDDFT for HF, LDA, and GGA SCF wave functions (#1349, #1885, #1814, #2156)
• UHF Hessians and gradients (#842)
• LIBxc density screening (#1860)
• Add MBIS charge partitioning (#1961, #2035, #2056, #2127)
• External potentials to CP-SCF solver (#2006)
• FMM and PE(ECP) (#2025)
• SAPT(DFT) supports hybrid XC kernel in dispersion (#1865)
• SAPT0-D routines, includes interface (#2081)
• Electrostatic embedding to FSAPT (#2131)
• Implement level shifts in RHF, UHF, CUHF, ROHF (#2225, #2237)

New External Libraries

• QCEngine - A QCSchema runner is now a required dependency since we use it for several interfaces (#1577)
  • DFTD3
  • MP2D
  • gCP
• CPPE - Polarizable embedding with environment modeled by multi-center multipole expansion with dipole-dipole polarizabilities at the expansion sites (#1401)
• ADC from ADCC callable from Psi (#1744, #1827, #1848, #1892, #1914)
• Enables use of GeomeTRIC optimizer in Psi (#1813)
• Interoperability via Molssi Driver (#1676, #1929, #2163)
• Psi4fockci (#1855)
• CCT3 (#1934)
• Interface to i-pi (#1057)
• BrianQC GPU module (#1893)
• Upgrade to Libint2 (#1721)
• Update RESP and PSIXAS (#2065)
• Move to Libxc5 (#1101, #2113, #2169, #2191)

Additional Non-Core Contributors to v1.4

@ramis, @jwaldrop107, @obrien951, @dsirianni, @Dpgibney, @derekmetcalf, @alenaizan, @susilehtola, @tovestra, @jeffschriber, @zachglick, @maxscheurer, @chapincavender, @PhillCli, @mdamer, @katrinleinweber, @mfherbst, @edeprince3, @konpat, @kcpearce, @Icyyork, @timostrunk, @shivupa, @taylor-a-barnes, @shannonhouck, @bennybp, @tomspur, @jgonthier, @sjrl, @kis-gergely-dzsi, @ferchault, @andyj10224, @psi-rking, @SimonBoothroyd, @yxie326, @VHchavez, @nlk36701, @edeustua, @leeping, @mquevill, @lazaroid, @sgoodlett

Performance Optimizations

• omega exchange can now be computed with MemJK algorithm. By not having to shunt range-separated functionals to DiskJK even when they’d fit in memory, 30-40% performance improvements seen (#1749)
• Big performance improvement to DF SCF Hessian (#1805)
• Omega combine algorithm for computing exchange terms (#1911)
• Optimize linalg::triplet (#2053)
• Thread external charge potential (#1946)

Details of Interest

See section at https://github.com/psi4/psi4/issues/1562#issue-416040173 that won’t fit here.

Bug Fixes

See section at https://github.com/psi4/psi4/issues/1562#issue-416040173 that won’t fit here.