Broaden

The functions CreateSpectra and CreateResonantSpectra have a Lorentzian broadening and no Gaussian broadening. This is inherent to the way we do the calculations as Green's functions $\frac{1}{\omega - H + \mathrm{I} \frac{\Gamma}{2}}$, with $\Gamma$ the full width half maximum Lorentzian line width.

The function Spectra.Broaden takes two parameters, an additional Lorentizan and a Gaussian broadening. These are applied successively and as such these are convolutions. The resulting function is a Voigt profile.