 Geometrical frustration

Geometric frustration occurs when the interaction graph prevents all local preferred configurations from being satisfied simultaneously. Antiferromagnetic spins can be antiparallel on every bond of a bipartite graph, but three equal spins on a triangle instead minimize their total exchange by summing to zero, giving a coplanar $120$-degree arrangement.

Geometrical frustration is a concept that arises in condensed matter physics, particularly in the study of magnetic materials and spin systems. It refers to a situation where the geometric arrangement of interactions among particles (such as spins) prevents them from simultaneously minimizing their energy, leading to a highly degenerate ground state with many possible configurations.