orca-step 2026.7.10

A SEAMM plug-in for ORCA

SEAMM ORCA Plug-in

A SEAMM plug-in for ORCA

• Free software: BSD-3-Clause

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

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

Features

A SEAMM plug-in for ORCA, a general-purpose quantum-chemistry program, with an emphasis on accurate molecular calculations such as DLPNO-CCSD(T).

Like the MOPAC and Gaussian steps, the ORCA step is a sub-flowchart: you add an ORCA node to your flowchart and then build a small sub-flowchart of ORCA capabilities inside it. Initially the available capabilities are:

• Energy – a single-point energy.

• Optimization – a geometry optimization.

Further capabilities (frequencies, properties, …) will be added.

Methods are described by the step’s metadata and can be set either explicitly in the ORCA dialog (similar to the Gaussian step) or, by default, taken from a preceding Model Chemistry step. Basis sets default to ORCA’s built-in families (Pople, Dunning cc, and Karlsruhe def2), with the Basis Set Exchange available as a planned opt-in source.

Acknowledgements

This package was created with the molssi-seamm/cookiecutter-seamm-plugin tool, which is based on the excellent Cookiecutter.

Developed by the Molecular Sciences Software Institute (MolSSI), which receives funding from the National Science Foundation under award CHE-2136142.

History

2026.7.10 – BSSE: energy-only mode (enables CCSD(T))

• New Compute the gradient control on the BSSE sub-step. With it set to no (energy only), the counterpoise correction runs without a gradient, which is cheaper and works for methods that have no analytic gradient in ORCA – notably CCSD(T) / DLPNO-CCSD(T) – for gold-standard counterpoise interaction energies. The default (yes) is unchanged and still produces the corrected energy and gradient for MLFF training.

2026.7.9.2 – BSSE (counterpoise) sub-step

• New BSSE sub-step: the counterpoise-corrected (Boys–Bernardi) energy and gradient of a two-fragment complex, in a single ORCA run, for BSSE-free machine-learned-force-field training data. It drives ORCA’s Compound facility (the BSSEGradient script by D. G. Liakos & F. Neese).

• Reports the BSSE-corrected energy, the uncorrected (raw) energy, and the correction (in E_h and kcal/mol), plus the corrected gradient; each can be saved from the Results tab.

• Fragments are found automatically from the two molecules in the structure (so it works directly on a Dimer Builder dimer) or specified by atom; an option relaxes the free monomers before the correction.

• First version: a neutral, closed-shell complex of exactly two fragments with an ORCA-internal basis set. Any analytic-gradient method works, including dispersion-corrected and double-hybrid DFT and MP2.

2026.7.9.1 – SCF SThresh control on the Energy step

• New SCF SThresh control: set ORCA’s SCF convergence threshold (the %scf SThresh value, in E_h). Leave it at default to let the SCF convergence preset (or ORCA’s own default) govern SThresh, or give an explicit value – e.g. ORCA’s nominal 1.0e-07 – to write it out and override whatever the preset would otherwise set. Lower it for a tighter SCF (smoother energies and forces), raise it to converge more loosely. Available on the Energy and Optimization sub-steps.

2026.7.9 – MDI engine, integration-grid and SCF controls, and config fixes

• ORCA can now be driven as a persistent MDI engine, so steps that set up a model chemistry and evaluate it at many geometries (for example the Dimer Builder’s energy-based contact search) can use ORCA – for methods with an analytic gradient. Set this up with a Model Chemistry step; the ORCA step does not need configuring for it.

• New Integration grid control: choose ORCA’s grid preset (DEFGRID1, DEFGRID2, or DEFGRID3), or leave ORCA’s default.

• New SCF convergence control: choose the convergence-tolerance preset (SLOPPYSCF … EXTREMESCF), or leave ORCA’s default. It defaults to TIGHTSCF for smooth energies and forces (previously this was applied via the extra-keywords default, which is now empty).

• Bugfix: a $variable typed into the basis-set field (e.g. to vary the basis in a Loop) is now expanded to its value instead of being passed to ORCA literally.

• Bugfix: the pre-run description of a step showed the basis as a raw dictionary; it now shows the basis name.

• How to find and launch ORCA – its executable path and, for parallel runs, the OpenMPI library directory – now lives in ~/SEAMM/orca.ini (a template is created on install). The [orca-step] section of the main SEAMM configuration keeps only the user run options (ncores, memory). NOTE: if you previously set library-path (or a path) in the [orca-step] section, move it into ~/SEAMM/orca.ini.

2026.7.8 – Ordered basis-set list and complete-basis-set (CBS) extrapolation

• The basis-set list is now ordered by family and, within a family, into valence / polarization / diffuse ladders that each rise DZ -> TZ -> QZ -> 5Z, so a sensible progression is a single ladder read top to bottom.

• New complete-basis-set (CBS) extrapolation on the Energy step: set ‘Basis-set extrapolation’ to 2/3, 3/4, or 4/5 and pick a family (cc, aug-cc, def2, or ANO). This is a single ORCA job (its Extrapolate keyword) that runs both basis sets and extrapolates the SCF and correlation parts. When it is on, the fixed basis set is ignored, and gradients are not available (ORCA has no gradient for an extrapolated energy).

• The CBS control is hidden for the Optimization step, which needs a gradient that an extrapolated energy does not provide.

2026.7.6.1 – Bugfix: parallel execution and DFT functionals via Model Chemistry

• Bugfix: the library-path (and orca-path) settings were read under the wrong key and so were ignored; they are now applied. The matching OpenMPI ‘mpirun’ (the sibling ‘bin’ of library-path) is put on PATH so ORCA launches its workers with the correct OpenMPI – a mismatched one (e.g. a newer system OpenMPI) causes parallel runs to abort with a BLAS-ERROR. The loader variables are also exported inside the run command so they survive macOS System Integrity Protection. (On macOS ORCA does not pass DYLD_* to its MPI sub-processes, so the OpenMPI libraries must additionally be on the default loader path, e.g. symlinked into /usr/local/lib; see the User Guide.)

• Bugfix: the DFT functionals are again selectable through the Model Chemistry step (each functional is offered as a method); this regressed when the functionals moved out of the method list. Keywords containing ‘/’ (e.g. REVDSD-PBEP86-D4/2021) appear with ‘_’ in the model-chemistry string, since ‘/’ is reserved there, and are translated back to the real keyword when the calculation runs.

2026.7.6 – All ORCA functionals, forces, database properties, and parallel execution

• Density functional theory now offers the complete set of ORCA functionals (117 of them), organized by type: pick a functional type (local, GGA, meta-GGA, hybrid, range-separated hybrid, or double-hybrid) and then the functional itself, including the double hybrids such as REVDSD-PBEP86-D4/2021.

• Gradients (forces) are produced with the correct ORCA method automatically: the analytic gradient where ORCA has one, or the numerical gradient where it does not (for example DLPNO-CCSD(T), and the non-self-consistent wB97M(2) and wB97X-2 functionals). A note is printed when the slower numerical gradient is used.

• Results can now be saved to the property database, including the gradient, the dipole-moment vector, the Mulliken, Löwdin, and Hirshfeld charges, the Mayer valences, and the rotational constants, in addition to the energies and other scalar results.

• The curated basis-set list has been filled out across the Pople, Dunning (correlation-consistent), and Karlsruhe def2 families, including their diffuse and minimally-augmented variants.

• Choosing ‘Basis Set Exchange’ as the basis-set source now opens the picker directly (it remains available from the ‘…’ button as well).

• ORCA runs in parallel by default, using the cores the machine or batch job provides. The number of cores and the memory per process can be set in the [orca-step] section of orca.ini (the ncores and memory options); parallel runs need ORCA’s OpenMPI runtime, whose location can be given with library-path.

• Documentation: a full User Guide covering methods and functionals, basis sets, forces, saving results, and parallel execution.

2026.6.28.1 – A Basis Set Exchange basis-set picker

• The basis set now uses the shared Basis Set Exchange picker: type a name, pick a common one from the list, or press ‘…’ to browse any basis from the Exchange, filtered to the elements you select on a periodic table. A choice from the Exchange is stored as ‘bse:NAME’, and the element selection is remembered so the picker is restored when the flowchart is reopened.

• Bugfix: the basis-set source control no longer appears on its own when the model chemistry is used; it is shown only with an explicit method and basis.

2026.6.28 – Properties, gradients, citations, and wavefunction export

• Reports many properties from a single calculation: HOMO/LUMO (and the next orbitals) and the gap, the dipole moment, rotational constants, <S^2>, the Mulliken, Löwdin, and Hirshfeld atomic charges, the Mayer bond orders and valences, and the optional dipole polarizability.

• The Mayer bond orders and Hirshfeld charges can be written to a CSV file and applied to the structure.

• Energy gradients can be requested and are written to Results.json for use by driver steps such as Thermochemistry and Reaction Path.

• Full citations for each run: the ORCA program, the DFT functional (from the ORCA manual), the basis set (via the Basis Set Exchange), and the supporting integral and exchange-correlation libraries.

• Basis sets can be taken from the Basis Set Exchange, including a ‘bse:NAME’ shorthand that forces a single basis from the Exchange.

• Can write an analytic wavefunction (.wfx, via orca_2aim) for a following Atomic Charges step to partition into DDEC6 charges.

• Fixed: the Results tab in the GUI was empty; it now lists the available results to save to variables, tables, or JSON.

2026.6.27 – Initial release of the ORCA step

• A sub-flowchart ORCA plug-in with Energy and Optimization sub-steps.

• Single-point energies and geometry optimizations, including DLPNO-CCSD(T).

• The method and basis set can be set explicitly, or taken from a preceding Model Chemistry step. Basis sets use ORCA’s built-in families.