Füllparameter

Füllparameter is a dimensionless quantity used in various scientific fields to describe the degree to which a system is occupied or filled relative to its capacity. It represents the ratio of the actual amount of a component, particles, or occupancy to the maximum possible amount that the system can accommodate. In many contexts, the Füllparameter corresponds to the concept of filling level, coverage, or density of filling.

In mathematical terms, the Füllparameter is often written as a ratio or average occupation. Common forms include ν = N_filled / N_max, or θ = number of occupied sites divided by total sites. In many-body physics, the average occupation per site is written as ⟨n⟩, and the filling factor is the mean value of ⟨n⟩ across the system. Specific domains provide concrete instances: in the quantum Hall effect, the filling factor ν denotes the number of filled Landau levels relative to their degeneracy; in adsorption and surface science, the term corresponds to the surface coverage, often denoted as θ.

Füllparameter appears in condensed matter physics, surface chemistry, and materials science to relate microscopic occupancy to macroscopic properties. It helps describe how interactions, phase behavior, and transport properties depend on how fully a system is populated. A higher Füllparameter typically indicates greater occupancy, which can drive changes in conductivity, optical response, or reaction kinetics. It is related to related concepts such as filling factor, occupancy, and coverage.

See also: filling factor, occupancy, surface coverage, filling degree, Füllgrad, Füllfaktor.