SynopsisA new method for a complete theoretical description of Interatomic Coulombic decay (ICD) in large polyatomic rare-gas clusters will be presented. This original method combines the projection-operator formalism of resonant scattering theory, the diatomics-in-molecules technique and a surface hopping algorithm. Such combined approach has fairly low computational costs and constitutes an efficient tool for studying ICD in polyatomic clusters. Benchmark examples will be given to illustrate the method. Results on ICD in large rare-gas clusters will finally be reported.