Radial profile of radiative force (blue lines) for different molecular cloud models M4 (left panel) and M7 (right panel)with an outer radius of R_out = 5 pc and a constant dust temperature of T_d = 20 K simulated with cluster models C3 through C7 in half steps.The blue band represents the same simulations with the absorption and reprocessing of radiation switched off (C_abs = 0 cm²), while the green bands result from the same simulations with an instantaneous redistribution of radiation (C_sca = 0 cm²).