The reaction force. A scalar property to characterize reaction mechanisms

The reaction force is a global property of a chemical reaction that arises when applying the Hellmann-Feynmann theorem to the potential energy surface that links reactants, products and transition states. In the present work, the reaction force is defined rigorously from the cartesian components coming out from all forces exerted over each atom of a molecular system during the chemical reaction; it is demonstrated that the reaction force is a scalar property.