Tauc-Lorentz model

Navigation:  The optical model > Defining Materials > Material types > KKR dielectric function models > Susceptibilities >

Tauc-Lorentz model

Previous pageReturn to chapter overviewNext page

Another suggestion for an interband transition model was given by [Jellison 1998A].  This model is called the Tauc-Lorentz model and gives the following expression for the imaginary part of the susceptibility:

 

 

The 4 parameters of the model must be entered using wavenumber units (except for S which has the unit (1/cm)1/2) in the following dialog:

 

tauc_lor_dialog

 

The following assignments apply:

 

 

S

Strength (in the Jellison paper a constant A was used which is the square of S)

ωτ

Damping constant

ω0

Resonance frequency

ωGap

Gap energy

 

The following example shows the dielectric function obtained with this model (the parameters are those displayed in the dialog above) where a constant dielectric background of 1 has been added:

Note that the peak of the imaginary part occurs at the resonance frequency. Below the gap the imaginary part is exactly zero, i.e. there is no absorption.