Résumé
In this work, we present the efficient combination of Smolyak representations with time indepen-dent quantum mechanical approach using absorbing boundary conditions for the cumulative reac-tion probability calculations of a multidimensional reactive scattering problem. Our approach usesboth kinds of Smolyak representations (finite basis and grid) which drastically reduces the size ofthe basis representation for the cumulative reaction operator. The cumulative reaction probabilityis thus obtained by solving the eigenvalue problem within the context of reaction path Hamiltonianusing the compact Smolyak basis combined with an iterative Lanczos algorithm. Benchmark cal-culations are presented for reactive scattering models with a linear reaction coordinate and appliedto a 25D model highlighting the efficiency of the present approach for multidimensional reactiveprocesses.