Comparisons of the ΔU difference for a model modified with only a Gaussian function (blue) and a model modified with the defined function f (see Eq. (9)) composed of a Gaussian and an error function (orange). Top panel: comparison of the adiabats (P_modif = 10¹¹ dyn cm⁻², ΔP = 0.5, dρ = −0.06 for the blue curve & P_modif = 10^11.5 dyn cnr⁻², ΔP = 0.6, dρ = −0.05). Bottom panel: difference between the ΔU of the modified models and that of the reference model (MH13).