Cole–Davidson equation

The Cole-Davidson equation is a model used to describe dielectric relaxation in glass-forming liquids.

is the permittivity at the high frequency limit,

is the static, low frequency permittivity, and

is the characteristic relaxation time of the medium.

represents the exponent of the decay of the high frequency wing of the imaginary part,

The Cole–Davidson equation is a generalization of the Debye relaxation keeping the initial increase of the low frequency wing of the imaginary part,

Because this is also a characteristic feature of the Fourier transform of the stretched exponential function it has been considered as an approximation of the latter,[2] although nowadays an approximation by the Havriliak-Negami function or exact numerical calculation may be preferred.

in double-logarithmic representation are different it is considered an asymmetric generalization in contrast to the Cole-Cole equation.

The Cole–Davidson equation is the special case of the Havriliak-Negami relaxation with