Deprotonation of organic molecules are key processes involved in the rate limiting step of many chemical and biological processes. Their reaction mechanism depends on several factors such as the nature of the acid functional group (carboxyl, hydroxyl, etc.), the substituents of the molecule, and the type of solvent. However, despite their importance, the mechanism of these processes remain not well understood.<br/><br/>In this project we shall study the mechanism of deprotonation of different classes of organic molecules in different solvents by ab-initio simulations, elucidating also the role of the solvent and molecular substituents. Standard atomistic simulations techniques, such as molecular dynamics (MD), cannot be used for simulating these processes by brute-force because of the time scale involved: deprotonation is a rare event. This problem will be overcame using modern 'sampling' techniques, such as Temperature Accelerated Molecular Dynamics, the String Method, and Milestoning, adapting them to the study of deprotonation process and, more generally, to chemical reactions. These techniques allow to compute the reaction rate, characterize its mechanism(s), and calculate its free energy along the reaction path (i.e. free energy barrier) of chemical reactions in realistic conditions (i.e. in solution).<br/><br/>The present project will require expertise in both electronic structure calculations in condensed phase, of which the proposer is an expert, and statistical mechanics in which the scientist in charge (Prof. Ciccotti) is a well-known expert. This will allow the proposer to complement his competences by learning about modern concepts and simulation methods in the statistical mechanics theory of reactive events.