Dipole (ℓ = 1) asymptotic period spacing as a function of the effective temperature for the ONe evolutionary cooling sequence with mass M_⋆ = 1.29 M_⊙. The thick curve corresponds to the case in which latent heat and chemical redistribution caused by phase separation have been taken into account during crystallization (LH+PS case), the intermediate-thickness curve displays the case in which chemical redistribution caused by phase separation has been neglected (LH case), and the thin curve is associated with the case in which crystallization has been neglected (NC case). The palette of colors corresponds to the fraction of crystallized mass (M_c/M_⋆). Vertical dotted lines show the T_eff interval of the ZZ Ceti instability strip.