Face-Centered Cubic Crystals
The face-centered cubic (FCC) lattice is a close-packed structure adopted by many metals. Explore it in this live AIMS simulation.
The face-centered cubic lattice (FCC) is a cubic crystal system and a close-packed structure. Many common metals — such as gold, silver, copper, and aluminum — adopt this arrangement. Explore the FCC structure in the live AIMS model below.
How the Atoms Are Arranged
In a face-centered cubic crystal, atoms sit at all eight corners of a cube and at the center of each of its six faces. Every atom touches twelve nearest neighbors — a coordination number of 12 — and the atoms fill about 74% of the available space, the densest packing possible for spheres of equal size. This efficient packing is why FCC metals such as gold, silver, copper, and aluminum are typically soft, ductile, and easy to shape: their close-packed planes can slide past one another along many equivalent directions.
Simulated with the Embedded-Atom Method
Metallic bonding cannot be captured by simple pairwise springs, because the strength of the bond between two atoms depends on how many other atoms surround them. This simulation therefore uses embedded-atom method (EAM) force fields, in which each atom's energy includes a term for embedding it in the local electron density contributed by its neighbors. EAM potentials reproduce the elastic and structural properties of real metals far more faithfully than pair potentials, which is what makes a realistic molecular dynamics simulation of FCC metals possible here.
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