SEAMM Psi4 Plug-in

A SEAMM plug-in to setup, run and analyze quantum chemistry calculations using Psi4.

• Free software: BSD-3-Clause

• Documentation: https://molssi-seamm.github.io/psi4_step/index.html

• Code: https://github.com/molssi-seamm/psi4_step

History

2026.10.1 – Settings that depend on each other, and three bug fixes

• The dialogs show only the settings that apply with the current choices, and SEAMM’s flowchart tools use the same rules: the functional only for DFT; the frozen core only for correlated methods; a dispersion correction only from the functional’s own list; the damping, level-shift and second-order SCF controls only when switched on.

• BSSE no longer offers the 17 Energy settings it does not use (Psi4’s own SCF settings are used, and no plots are made), and Thermochemistry’s plots apply only when it uses its own settings.

• Bugfix: Thermochemistry right after Initialization tried to use the previous step’s method; it now uses its own settings.

• Bugfix: a functional given by its short name (e.g. a variable set to ‘b3lyp’) raised KeyError.

• Bugfix: keeping the dispersion choice valid in the dialog raised a TypeError.

• Documented in the user guide. Needs seamm 2026.10.1.

• Internal: CI now installs the package’s declared dependencies with uv rather than a conda test environment; seamm-exec, which it uses, is now declared.

2026.8.7 – Bugfix: catch a mis-assigned per-fragment BSSE charge before running Psi4

• The BSSE (counterpoise) sub-step now passes the cluster’s atomic numbers into seamm_bsse.validate_fragments, which checks that every fragment has an even electron count at its assigned charge. Previously, a per-fragment charge given to the wrong fragment (e.g. an ion’s charge assigned to its neutral partner instead of the ion) could still sum correctly to the complex’s own charge and pass validation, only to fail deep inside Psi4 once that fragment ran as an impossible odd-electron singlet. This is now caught up front with a clear message naming the offending fragment.

• Leaving fragment charges empty no longer always means all-neutral: if the structure carries per-atom formal charges (e.g. an ion marked with an SDF/MOL M CHG record, such as the Na+ in a Na+..H2O complex), each fragment now defaults to the sum of its own atoms’ formal charge. This covers monatomic ions (Na+, Cl-) and polyatomic ions (NH4+, BF4-) alike without the caller needing to spell out fragment charges at all – removing the main way to trigger the mis-assignment above in the first place. An explicit fragment charges still overrides it.

2026.8.4 – Added a BSSE (counterpoise) sub-step

• New BSSE sub-step: computes the counterpoise-corrected (Boys-Bernardi) energy and gradient of an N-fragment complex, with an independent charge per fragment – needed for ions, e.g. a Na+/Cl- pair or a Na+/Cl-/H2O cluster. A thin wrapper around Psi4’s own native N-fragment counterpoise driver (bsse_type=['cp', 'nocp']); requires the new seamm-bsse package for the fragment-definition/validation layer shared with orca_step’s own BSSE sub-step. Validated against real Psi4 and cross-checked against orca_step’s independently-implemented BSSE sub-step on the water dimer, charged ion/water pairs, and a three-fragment Na+/Cl-/H2O cluster – agreement to a few hundredths of a kcal/mol throughout.

2026.3.1 – Internal: switching from deprecated library pkg_resources to importlib

2025.3.9 – Optimization and thermochemistry enhancements

• Expanded the output to include gap, HOMO, LUMO, RMSD between initial and final structure for optimizations, dipole moment, etc.

• Added control for updating the structure after optimization.

• Added enthalpy of formation to the thermochemistry output for known basis sets.

• Updated the installation to work with recent changes.

2024.12.7 – Minor update due to changes in molsystem

• The molsystem was updated to improve the handling of properties. This required changes in this module to match the new molsystem.

2024.10.15 – Bugfix: error if used in a loop and previous directories deleted.

• The code crashed if called with a loop in the flowchart, and the last directory of a previous loop iteration was deleted before running the next iteration.

2024.10.5 – Enhancements and bug fixes for thermochemistry

• Improved GUI for thermochemistry so that it automatically recognizes whether it is after e.g. an optimization and configures appropriately.

• Fixed and issue with transferring the multipole moments to the JSON file

2024.7.30 – Enhanced results and fixed problem with psi4.ini

• Added to the results by using cclib to parse the output.

• If ~/SEAMM/psi4.ini did not exist the version that was automatically created was not complete, causing calculations to fail.

2024.5.23.3 – Added auxiliary codes that help Psi4

• Psi4 uses codes like DFTD4 and DFTD4 for parts of e.g. dispersion calculations. This release adds them to the Conda install SEAMM uses for Psi4.

2024.5.23.2 – Bugfix: incorrect name for gradients

• There was a typo in the name for the gradients, such that they could not be output to Results.json.

• The units for the energy and gradients in Results.json were incorrect.

2024.5.23.1 – Internal fix for creating Docker image.

2024.5.23 – Added standard energy and gradients to results

• Added ‘energy’ and ‘gradients’ to optional results to support e.g. Energy Scan

• Fixed crashing bug in description of the Energy substep.

2024.3.17 – Updated the installer

• Updated the installer to use the new version of the SEAMM installer.

• Finalizes installing either with Conda or Docker

2024.3.4 – Allowing short names for method and DFT functionals

• Added short names for the methods (Hamiltonians) and DFT functionals.

• Catch errors in Psi4 calculating properties for e.g. CISD(T) method

2024.2.29 – Completed support for containers

• Fixed issues with running amd64 containers on arm64 systems.

2024.1.11 – Changes to allow running in containers.

• Moved to the new executor and ensured it still runs directly.

• Fixed bugs in printing the summary output.

2023.8.23 – Fix for installation of Psi4

• Psi4 is now available on CondaForge, so install from there if requested.

• Psi4 crashes if asked to optimize and atom, so change to doing a single point energy is optimization is requested for and atom.

2023.8.22 – Enhancement of orbital plots

• Added structure to the orbital plots

• Fixed a bug if the default number of cores was not ‘available’

2023.6.4 – Enhancements

• Added thermochemistry substep to compute the vibrational and other corrections for thermochemistry.

• Added ability to create .cube files for plotting the density and orbitals.

2023.2.21 – Added control over SCF convergence

• Able to set convergence criteria.

• Options for damping. level shifting and second-order SCF

• Set default for number of steps for optimization to 6*nAtoms to make it more explicit.

2023.2.17 – Checking more thoroughly for errors in Psi4

• Check and throw errors for various issues when running Psi4, including whenever it does not complete successfully according to the output.

2023.2.16.1 – OptKing will not die!!!

• Yet another part needed to be removed.

2023.2.16 – Thoroughly removing calls to OptKing

• OptKing is causing compatibility issues, and is not currently being used in the Python, so am temporarily removing it.