• radiation biophysics
• molecular dynamics
• monte carlo methods
• flash radiotherapy
• ultra high dose rate

In this thesis, the combination between MC and MD is realized using the state-of-the-art implementation of the two methods. Concerning MC, we studied the impact of different physical parameters, like radiation quality and
fluence, affecting the inter-track distance for different spatiotemporal configurations of irradiation, on chemical evolution. For MD, the most advanced version of the atomistic reactive force field is used and tested versus their capability of reproducing reactions involving hydroxyl radicals. A detailed comparison of the outcomes from the two techniques is performed. On the technical level, a number of tools for interfacing codes and exchanging input-output data were created. This work also aimed at laying the foundations for a future extension capable of describing the cascade of physicochemical processes occurring, from the interaction of radiation to DNA damage and beyond. Such a method of investigation would be particularly suitable in the complex scenario of ultra-high dose rates irradiation.