Example of the abundance profile adjustment during the fitting process. The observed line profiles of H₂D⁺ are overplotted with the modeled ones using RATRAN toward the central position of the L183 core. Three different dynamical models were adopted, QE-BES, SIS and LP flow. The original abundance profiles (left panel) were adopted by Pagani et al. (2009) and cannot reproduce the central peak of the observations. Adjusting the H₂D⁺ abundance profile by applying a multiplication factor, resulted in a better reproduction of the observations for the LP and QE-BES models, while the SIS model failed to match the shape of the observed line profile.