For the decomposition of spectra, we use software Fityk. In it, a q-Gaussian function can be defined in the following manner: define Qgau(height, center, hwhm, q=1.5) = height*(1+(q-1)*((x-center)/hwhm)^2)^(1/(1q)) , where q=1.5 is the initial guessed value of the q-parameter. Parameter hwhm is the half width at half maximum of the component. And the q-BWF as: