Profiles of element abundances (top left corner) and diffusion coefficients (top right corner) (D_mix) at the first He flash. The solid lines are for the model with element diffusion, and the dashed lines are for model without element diffusion. The left and right panels at the bottom show the relative changes between the mean molecular weights (μ_diff and μ) with and without element diffusion, and between the mean molecular weight gradients (∇μ_diff and ∇μ) with and without element diffusion, respectively.