The Extensible Computational Chemistry Environment (ECCE, pronounced "etch-ā"; ecce is Latin for "behold") is a graphical environment for computational chemistry: build a molecule, set up a calculation, run it on your own computer or a cluster, and look at the results (orbitals, densities, vibrations, geometry optimisations), with every calculation kept in one place.
It works with ORCA, Gaussian, NWChem, MOPAC and xTB, and experimentally with GROMACS, CP2K and Quantum ESPRESSO; ECCE 9 also includes ECCE-QM, a small built-in Hartree–Fock/DFT program that needs nothing else installed. Calculations can be chained into workflows: for example, xTB finds a structure quickly and ORCA refines it, each step starting from the geometry of the one before. ECCE was developed at Pacific Northwest National Laboratory, which stopped supporting it around 2017; it is maintained here since, with PNNL's blessing.
More pictures and the full feature list: ECCE overview.
Download from the releases page.
- ECCE 9 (latest 9.4.6), for Linux, macOS and Windows: the recommended version. The macOS and Windows clients are experimental.
- ECCE 8.18.x (latest 8.18.14), Linux only: the older line, which still gets bug fixes.
| System | File | Install |
|---|---|---|
| Debian 13, Ubuntu 24.04 | ecce-client_…deb, ecce-server_…deb |
sudo apt install ./ecce-client_*.deb ./ecce-server_*.deb |
| RHEL/Rocky 9, Fedora | ecce-client-…rpm, ecce-server-…rpm |
sudo dnf install ./ecce-*.rpm (on RHEL/Rocky first sudo dnf install epel-release) |
| macOS | ECCE-…-arm64.dmg (Apple silicon) or …-x86_64.dmg (Intel) |
open it and drag ECCE to Applications; macOS refuses it at first: on macOS 15 and later open it once, then System Settings → Privacy & Security → Open Anyway (macOS 14 and earlier: right-click → Open), or run xattr -dr com.apple.quarantine /Applications/ECCE.app |
| Windows 10/11 | ECCE-windows-….msi |
double-click; at the SmartScreen warning choose More info → Run anyway |
Then start ecce (on macOS and Windows: ECCE in Applications or the
Start menu). Details for each system: Installing ECCE.
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Example set Workflows: a workflow of Na+(H2O)6 in which xTB optimises three arrangements (6+0, 5+1, 4+2) and ORCA r2SCAN-3c refines each result, opened from File > Open Example Calculations.
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Workflows (preview): File > New > Workflow... makes a set of calculations of any electronic-structure code (ECCE-QM, ORCA, Gaussian-16, NWChem, MOPAC, xTB, Quantum ESPRESSO, CP2K) drawn as a tree. Select a box and a code on the right to add a step that starts from the final geometry, charge and multiplicity of that box (several steps from one box are branches), and Launch Ready Steps launches every step whose source is Complete.
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xTB: GFN2-xTB, GFN1-xTB and GFN-FF through the
xtbprogram, as a new code in the code bar: energy and geometry optimisation, with an implicit solvent (ALPB or GBSA). The orbitals (energies, occupations and coefficients) are read from xtb's Molden file for GFN2 and GFN1; GFN-FF has no orbitals. Atomic charges, and a Vibration and a Geometry + Vibration run type with frequencies, IR intensities, normal modes and the thermochemistry (zero-point energy, enthalpy, Gibbs energy, T*S). The output of anxtbrun made outside ECCE can be imported from the Organizer, with the files xtb wrote beside it; the Getting Started set has an xTB water example, and the xTB help page describes the code. -
Results file: the
ecce-resultscommand converts orbitals from Molden, Gaussian fchk and ORCA files, and an ORCA Hessian, into one HDF5 file (results.h5) with a fixed orbital order, the basis for carrying orbitals and Hessians from one workflow step to the next; the results file help page describes it. -
ecce-launch: launch Ready calculations from the command line, inside the running ECCE session, with their stored machine, cores and wall time; it prints each job id (#687). -
Workflow joins: Ctrl-click a reactant, a product and a TS guess and choose Gaussian 16 or ORCA to make a QST3 (or QST2) or NEB-TS step; a step can start from a scan's last point, its maximum or any point. Example: an SN2 reaction, Cl⁻ + CH₃Br, from the reactant complex through a relaxed scan to the QST3 transition state and its IRC.
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Gaussian 16 IRC: points per direction, step size and direction in Runtype Details (#688).
The same pages are in ECCE under Help. To see it done first, the chem4eva YouTube channel has short videos with subtitles: installing ECCE, a first calculation with ECCE-QM (nothing else to install) and a first ORCA calculation.
- Installation: what you see the first time ECCE starts, and where your work is kept.
- Your first calculation: build, run and look at a calculation.
- Running codes on Linux, on Windows or on macOS: installing NWChem, MOPAC, ORCA and the others, and telling ECCE where they are.
- Importing a structure or a calculation that ran elsewhere.
Questions, and how you use ECCE, are welcome in
Discussions.
Run the session that goes wrong with ecce --bug. When it ends, ECCE
collects its logs into ~/ecce-bug-<time>.zip (no passwords, but host
names, user names and paths). Attach that to a
new issue, with what
you did and what you expected.
- Getting started: building, packaging, a central server for a group or class, TLS, the other deployment modes, upgrading from 8.x.
- Contributing: building from source, branches and releases, the roadmap, and how to help.
- Changes: what is new in 9.0 and in 8.x, and the release history.
- The wiki: where things are in the code, and the current work plan.
- Accessibility: what ECCE does for keyboard, screen reader and low-vision use, and how to report a barrier.
Please cite the DOI for all versions, 10.5281/zenodo.23281771; each release also has its own DOI there. GitHub's "Cite this repository" button gives the reference in APA and BibTeX form.
ECCE is free software under the Educational Community License 2.0; see
LICENSE. For the use of the name, see TRADEMARKS.md.