Comparison of the observations and radiative transfer modeling of the chemical network results. The black line shows the DCO⁺ observations integrated over the southern clump, with the gray solid and dashed lines showing the 1σ and 4σ levels, respectively. Models are referred to by test, abundance profile (Constant “C” or Drop “D”) and case. Color lines show tests 1 (blue), 2 (green), 3 (orange) and 4 (purple) for the top left panel, and cases a (blue), b (green), d (orange) and f (purple) for the other four panels.