The characteristics of electronic decay processes are influenced by the environment. Ionization and excitation energies are altered by the delocalization of the excited state over multiple entities as well as electronic (de)stabilization. The latter is famously utilized in Auger electron spectroscopy.
The lifetimes can be severely changed as well. For Interparticle Coulombic Decay processes (ICD) the decay width depends linearly on the number of closest neighbours and is further increased by other decay partners further away. This effect can decrease the lifetime by an order of magnitude and thereby allow the ICD to outperform the Auger-Meitner process in some cases.
We have developed the program HARDRoC, which we use to study the effect of the environment on ICD processes. Its development allowed to increase the system size from 13 atoms to several thousand atoms.