2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/130389The destruction of anomalous diffusion of the Harper model at criticality, due to weak nonlinearity $χ$, is analyzed. It is shown that the second moment grows subdiffusively as $<m_2> \sim t^α$ up to time $t^*\sim χ^γ$. The exponents $α$ and $γ$ reflect the multifractal properties of the spectra and the eigenfunctions of the linear model. For $t>t^*$, the anomalous diffusion law is recovered, although the evolving profile has a different shape than in the linear case. These results are applicable in wave propagation through nonlinear waveguide arrays and transport of Bose-Einstein condensates in optical lattices.6 pages, 5 figures. Revised and published in Phys. Rev. BOther Condensed MatterDisordered Systems and Neural Networkstext