The most widely used alternative to a Gaussian fit is a Breit-Wigner-Fano (BWF) line for the G peak and a Lorentzian for the D peak". The BWF, which is asymmetric, can be reduced to a Lorentzian line shape for its specific feature parameter limit to 0. As observed by Ferrari and Robertson, the BWF curve has an increased power tail for lower frequencies. This allows the use of BWF lines to account for residual intensities, avoiding extra peaks. "The BWF+Lorentzian line pair is therefore an excellent means to fit Raman spectra of all carbons, from graphite to ta-C [tetrahedral amorphous carbon]. A Lorentzian line shape is used for the D peak as it is from the same family as the BWF line, while the various enhancement mechanisms for the D peak are consistent with a Lorentzian. However, any wide low-frequency tail of the BWF line will push the D peak to lower frequencies as the disorder increases. This significantly decreases the D peak size compared to a two-Gaussian fit. … . On one hand, smaller aromatic clusters have higher modes and shift D upwards. … Another important issue … [of the BWF lineshape], is that the maximum of the BWF line is not at ω0 but lies at lower frequencies … [However] The asymmetric BWF line shape is appropriate for the G peak due to the asymmetry of the VDOS of graphite or amorphous carbons towards lower wave numbers" , and references therein).