Physical conditions (n_H, T_d, χ and A_V) and abundances of the main oxygen-, carbon- and nitrogen-bearing species for the single parcel from Sect. 5.1, as function of time before the end of the collapse (left) and as function of horizontal position during the collapse (right). The grey bars correspond to the points A, B and C from Fig. 3. In each panel, the parcel essentially moves from right to left.