Persistence length

In polymer physics, the persistence is a measure of the stiffness of a polymer chain.

In a polymer melt or solution of a polymer assumes a random ball shape. Depending on the nature of the chemical bond between the monomers is a polymer chain rather " stiff" or more flexible, resulting in a more or less loose coil conformation. Denotes a linear coordinate along the contour of the chain and a unit vector that specifies the local orientation of the chain, the correlation function is

Strive for great against zero. The more compact the polymer coils, the faster decreases the correlation function. The persistence of LPS as a measure of the compactness of the coil structure is defined as the distance along the contour of the chain, for which the area is divided among the correlation function K in two equal parts,

(L here is the total length ( = contour length) of the polymer chain).