Same as Fig. 1, but for comparison of different ways to evaluate ∇_rad. The profiles are 1D models calibrated using CM with the VAL-C T(τ). The black solid line was obtained by the method adopted to the 3D α calibration, using Eq. (1) and considering convection both in the optically thin and thick layers. The dashed lines were obtained by a method adopted by some evolution codes (see the text).