Periodic boundary conditions (PBCs) are a set of boundary conditions which are often chosen for approximating a large (infinite) system by using a small part called a unit cell. PBCs are often used in computer simulations and mathematical models. The topology of two-dimensional PBC is equal to that of a world map of some video games; the geometry of the unit cell satisfies perfect two-dimensional tiling, and when an object passes through one side of the unit cell, it re-appears on the opposite side with the same velocity.
Periodic boundary conditions (PBCs) are a set of boundary conditions commonly used to simulate large systems by using a small part called a unit cell. PBCs are extensively utilized in computer simulations and mathematical models. The topology of two-dimensional PBC resembles that of a world map from certain video games; the geometry of the unit cell ensures perfect two-dimensional tiling, and when an object moves through one side of the unit cell, it re-enters on the opposite side with the same velocity.