Calango is a desktop application for computational materials science. It brings three things together in one window: an interactive viewer for building, editing and inspecting atomic structures; a calculator-agnostic environment for setting up, orchestrating and running simulations; and a set of viewers that turn the output of those simulations back into figures you can read.
Molecules, crystals, surfaces and disordered systems are shown on a 3D canvas that stays fluid at tens of thousands of atoms, and every view on it is ready for publication.
- Representations and color. Ball-and-stick, space-filling and wireframe, with coloring by element, coordination number, generalized coordination number or any per-atom scalar field, plus live legends, gradient bond coloring, force and velocity arrows, and magnetic-moment overlays.
- Direct manipulation. Six mouse modes — rotate, pan, select, insert, distance, angle — with single-key shortcuts, ray-cast picking, rubber-band selection, snapshot undo and redo, an interactive bond editor, and a periodic-table element picker.
- Builders for real materials problems. Surface slabs with an interactive Miller-index canvas; liquid and gas interfaces and ionic solutions packed to a target density; dislocations, stacking faults, twins, bicrystals and Voronoi polycrystals; nanotubes, nanoribbons, monolayers and nanoparticles; special quasirandom structures; polymers, water and ice, and adsorbate coverages.
- Molecule and crystal libraries. Common molecules and crystal prototypes are one dialog away, ordered by how often they are what you need, and editable the moment they appear.
- Studio lighting and depth. Up to four directional lights with a three-light studio default, ambient occlusion, depth of field and distance fog, all tuned live.
- File formats without friction. Everything the Atomic Simulation Environment reads and writes — CIF, POSCAR, extended XYZ, Quantum ESPRESSO, LAMMPS, Gaussian, SHELX and more — plus project files that restore a whole multi-tab session.
- Publication output. Off-screen renders up to 8192 px with transparency, turntable and trajectory animations, ray-traced scenes matching the live viewport, and Alembic export for Blender, Houdini and Maya.
A staged wizard collects the physics, generates a complete and editable Python script, and hands it to a runner that executes it locally, queues it behind other jobs, or submits it to an HPC cluster. The script is always visible: read it, edit it in place, or export it and run it unchanged on any machine.
- Calculator-agnostic. DFT and quantum chemistry (GPAW, Quantum ESPRESSO, VASP, ABINIT, CP2K, FHI-aims, SIESTA, OpenMX, FLEUR, NWChem, ORCA), semi-empirical tight binding (xTB, DFTB+), classical potentials and molecular mechanics (LAMMPS, GROMACS, Amber, EMT, Lennard-Jones, ASAP), and machine-learning potentials (MACE, CHGNet, MatterSim, FAIRChem, NequIP, Allegro, DeepMD-kit) — a continually expanding library, in which every engine offers the parameters it actually has rather than a lowest-common-denominator form.
- The full task matrix. Single-point energies, geometry optimization, molecular dynamics with the complete thermostat set and simulated-annealing schedules, phonons, electron-phonon coupling and superconducting transition temperatures, absolute free energies by thermodynamic integration, Monte Carlo, nudged elastic band, cluster expansion and alloy thermodynamics, parameter convergence sweeps, and machine-learning potential training.
- Orchestration. Chain calculations on a node-graph canvas — relax, then converge, then compute a spectrum — passing geometries and converged ground states from node to node, with per-node status, batch fan-out over many structures, and resume from the point of failure.
- Remote HPC execution. Connect over SSH and Calango stages the script and structure, writes a SLURM, PBS or SGE wrapper, submits it, polls the queue, streams the remote log, and downloads the results when the run finishes.
- Live monitoring. Energy, temperature, force and pressure stream into plots while a job runs, molecular-dynamics trajectories appear in the viewport frame by frame as they are computed, and new jobs queue instead of being refused.
Finished runs are read back into the application, so results arrive as interactive figures rather than as output files waiting to be post-processed.
- Electronic structure. Band structures with projected density of states, fatbands and irreducible-representation labels; band unfolding for supercells; Fermi surfaces and topological invariants; Wannier functions; G₀W₀ quasiparticle corrections; Hubbard U by linear response; X-ray absorption spectra.
- Optical and vibrational spectra. Linear, 2D and nonlinear optics, including second-harmonic generation, shift current and the intraband Drude response of metals; phonon dispersions and densities of states; Raman and infrared spectra with mode symmetry labels.
- Thermodynamic properties. Phonon free energy, entropy and heat capacity; absolute free energies from thermodynamic integration, with autocorrelation-corrected error bars; configurational entropy and order-disorder temperatures for alloys; formation-energy convex hulls.
- Structure and chemistry. Radial distribution functions, structure factor, simulated X-ray diffraction, bond statistics, coordination numbers, short-range order, local entropy, velocity autocorrelation, partial charges, charge-density differences, and charged-defect formation energies.
- Volumetric fields. Isosurfaces, slice planes and dual-field potential maps from cube, CHGCAR, LOCPOT, PARCHG, ELFCAR and XSF grids, with mesh export for external renderers.
- Convergence and run artifacts. Parameter sweeps plotted against the quantity being converged, and every run's log, metrics and output files one click away.
Prebuilt installers are published for Linux and macOS, each accompanied by a .sha256 checksum file.
Install the downloaded package with apt rather than dpkg -i, so that its dependencies are resolved for you:
sudo apt install ./calango_*_amd64.debThis provides the calango command, a desktop launcher, and a file association for .calproj project files, so double-clicking a saved project opens the whole session.
Open the downloaded .dmg and drag calango.app onto the Applications shortcut shown beside it. The image mounts without a license prompt, and the application runs on Apple Silicon without any further setup.
Distribution builds are signed ad hoc rather than notarized, so the first launch needs right-click, then Open, to get past Gatekeeper. Subsequent launches are normal.
| Resource | Covers |
|---|---|
| Sphinx manual (ReadTheDocs) | The full manual: builders, wizards, calculators, analysis, orchestration, remote execution, gallery, and building from source |
| User Guide (PDF) | The complete user guide, including a start-to-finish silicon tutorial |
| Packaging Guide (PDF) | How the installers are produced and what each one bundles |
Calango is released under the MIT License. Copyright © 2026 Leandro Seixas Rocha.
We thank financial support from INCT Materials Informatics (Grant No. 406447/2022-5).