In Thibault et al. we find mentioned the role of the apparatus, given as Gaussian. When the VP approach is used, many researchers assume that the Gaussian in the convolution is coming from the apparatus, with the result of a pure Lorentzian profile for the photonic emission. However, other effects, such as the Doppler effect considered in Thibault et al., with Gaussian influences participate to the broadening. Moreover, the Dicke effect exists producing a narrowing of Doppler broadening. The Dicke Effect, that is the "collision narrowing", is the following. In the case that the mean free path of an atom is quite smaller than the wavelength of the radiative transition, a narrowing of the line is produced. The atom is changing its speed and direction several times during photonic emission or absorption. In average on the different Doppler states, we find that the atomic line width is narrower than the Doppler width . "Of course, the choice of an appropriate line shape function is not a purely theoretical exercise and must be guided by fits to high accuracy measurements, which also need to consider the appropriate instrumental line shape function" . About the instrumental function and its role in the choice of the line shape, no discussion is given by Tennyson and coworkers.