https://doi.org/10.1351/goldbook.08229
Function \(y = a/(b^{2} + x^{2})\) where \(a\) and \(b\) are constants.
Note: If \(x\) is replaced by \(\tilde{\nu} - \tilde \nu_{0}\) this function yields a Lorentzian band centered at \(\tilde{\nu}_{0}\).