In order to use a material in SCOUT you have to define its optical constants (see below). In addition, you can define several other quantities such as thermal conductivity, density or deposition rates which may be required by some SCOUT or CODE computations. These numbers are stored together with the material's optical constants. Each material window has a menu item called Properties which has submenu commands to edit the available material properties.

Optical constants

In  most cases it is the electric field of the probing light wave that interacts with the sample. Hence excitations can be observed in optical experiments that are going along with a polarization. The polarization P induced by an externally applied electric field E in a homogeneous material is given by the electric susceptibility χ:

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The dielectric function ε which connects the dielectric displacement and the electric field vector is closely related to the susceptibility:

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The frequency dependence of the susceptibility is very characteristic for a material since it incorporates vibrations of the electronic system and the atomic cores as well as contributions from free charge carriers.

The complex refractive index n + i k is the square root (with positive imaginary part) of the dielectric function. Both the dielectric function and the refractive index are called optical constants. Internally SCOUT uses the dielectric function for all computations. In a material's window you can display both quantities, as described below.

The list of materials in SCOUT can exchange objects with a database of materials.

The SCOUT software offers several ways to define the frequency dependence of real and imaginary part of the dielectric function. You can import fixed data sets, i.e. tables of real and imaginary part for several spectral points, or you can setup models that give some mathematical expressions for the optical constants.

Optical constants can be displayed in various ways: As dielectric function or complex refractive index n + i k. In addition you can show the absorption coefficient α or the energy loss function.

The following sections give more details on the individual types of materials available in SCOUT:

•Imported dielectric function (fixed data sets)

•Dielectric function model

•KKR dielectric function models

•Master models

•Effective dielectric functions