Comparison of the simulation results generated by two solvers. The radiative rate-coefficient distributions (R₁₂) produced by the BESSER and linear solvers are shown in panels (a) and (c), respectively, while panel (e) compares the distributions extracted along the dashed line depicted in panels (a) and (c). Similarly, the level-population distributions (n₂) obtained from the two solvers are presented in panels (b) and (d), respectively, with panel (f) showing the corresponding comparison along the dashed line. All results correspond to t = 100 s. The rate coefficients at high temperatures (T > 0.2 MK) were manually set to zero to emphasize the results in the lower atmosphere.