Optimal L2 convergence of renormalized Crank–Nicolson mass lumping fems for the Landau–Lifshitz equationXinping Gui, Yiwei Jiang, Jilu Wang and Lihong YinESAIM: M2AN, 59 6 (2025) 3341-3362DOI: https://doi.org/10.1051/m2an/2025090