My research work is focused on the interface between molecular mechanics (MM) and quantum mechanics (QM). In particular, I develop software and methods that allow parametrization of MM force fields by fitting to QM data, as well as hybrid methodologies that combine the efficiency of MM-based simulations with the accuracy of the QM theory. This research has proven to be of paramount importance in a wide range of applications such as, e.g., conformational analysis, drug-design, and free energy calculations.