The optical model > Defining Materials > Material types > Dielectric function models > Susceptibilities

In the case of doped semiconductors the charge carriers set free by the donors or acceptors can be accelerated by very little energies and hence do respond to applied electric fields with frequencies in the infrared region. A simple expression for the susceptibility of free carriers (which is also applicable to metals, of course) is given by the so-called Drude model where the carrier concentration and a damping constant enters:

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The parameters plasma frequency and damping constant can be set in the corresponding SCOUT dialog:

drude_dialog