Main differences in the properties of the core of the models between the present calculations and those of R12. Upper panel: chemical profile of O at the CO-core regions of a DA WD model with M_⋆ = 0.5932 M_⊙, T_eff ∼ 12 000 K, and a thick H envelope, for the case of the present calculations (solid black line) and the R12 computations (dashed black line). Middle panel: Ledoux term B at the region of the O/C interface, B_OC, of the same model depicted in the upper panel, along with the artificial situations of B_OC/2, B_OC/4, and B_OC = 0. Lower panel: logarithm of the squared Brunt–Väisälä frequency for the same cases considered in the middle panel.