Hartree–Fock, DFT and GFN2-xTB on small molecules: orbitals, density and electrostatic surfaces, and vibrational modes, computed in your browser.
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Computed in your browser with OCC v0.9.6. Nothing is uploaded. If you use it, please cite OCC. About
Everything runs on your machine. OCC, compiled to WebAssembly, does the quantum chemistry in Web Workers; nothing you enter is uploaded. The only network request is the optional PubChem lookup, which goes straight to PubChem.
A run solves the SCF equations (or GFN2-xTB’s tight-binding equivalent) for the method you pick, and can optimise the geometry and compute harmonic frequencies. Orbitals, densities and the electrostatic potential are evaluated by OCC on grids or isosurfaces around the molecule and drawn in the browser. The 3D view and task handling come from the CrystalExplorer packages.
Keep molecules small: the cost grows steeply with the number of basis functions. GFN2-xTB copes with larger ones.
If you use this in your work, please cite OCC:
Spackman, P. R. (2026). Open Computational Chemistry (OCC) – A portable software library and program for quantum chemistry and crystallography. Journal of Open Source Software, 11(117), 9609. doi:10.21105/joss.09609