FIGURE 2 Formation mechanism of DBU/EG multimer absorbents and DBU/EG/H2S complexes. (a), (d), (g) and (j) most stable structures with minimum energy for DBU-EG, DBU-2EG, DBU-EG-2H2S complexes and DBU-2EG-4H2S complexes, respectively. (b), (e), (h) and (k) plot of sign (λ 2)ρ vs RDG for DBU-EG, DBU-2EG, DBU-EG-2H2S complexes and DBU-2EG-4H2S complexes, respectively. (c), (f), (i) and (l) gradient isosurfaces for DBU-EG, DBU-2EG, DBU-EG-2H2S complexes and DBU-2EG-4H2S complexes, respectively.