Brendel–Bormann oscillator model

The Brendel–Bormann (BB) oscillator model is a mathematical formula for the frequency dependence of the complex-valued relative dielectric permittivity, also known as the dielectric function. The model has been used to fit the complex refractive index of materials with absorption lineshapes exhibiting non-Lorentzian broadening, such as metals and amorphous insulators, across broad spectral ranges, typically near-ultraviolet, visible, and infrared frequencies.

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