A Bravais lattice is the repeating point pattern of a crystal.
Simple cubic places atoms only at cell corners; body-centred cubic
(BCC) adds one atom at the cell centre; face-centred cubic (FCC)
adds one at the centre of every face. Growth here mimics
nucleation: new unit cells attach to the surface over time.
Real crystals are rarely perfect: point defects such as
vacancies (a missing atom at a lattice site), interstitials and
substitutions form as the crystal grows or is heated. The
"Defects" toggle below simulates vacancies by randomly leaving a
small fraction of lattice sites empty as the crystal grows,
creating visible gaps in the otherwise regular pattern.
- Lattice type — switch between simple cubic, body-centred and face-centred arrangements.
- Pause/Resume growth — freeze or continue atom-by-atom nucleation.
- Growth rate — controls how quickly new atoms attach to the growing crystal.
- Defects — toggles random vacancy defects, tracked live in the Defects counter.
In real materials, vacancy defects matter enormously: they let
dopant atoms diffuse into semiconductor wafers (enabling
transistor manufacturing), and dislocations pinned by vacancies
are a major factor in the mechanical strength and ductility of
metals.