Laverdure, Laura Bray2015-01-272015-01-272015-01-27https://laurentian.scholaris.ca/handle/10219/2311A generalized electronic diabatic model for chemical reactions includes a physical mechanism for the transition from a reactant-like to a product-like quantum state, namely, an external field. In our model, an external electric field couples states and modifies effective potential energy surfaces thereby allowing to treat a reaction as a fully quantum process. Through semi-classical models of two-state reactions, we show that we can control the identity of the most stable nuclear configuration by varying the form and intensity of the external field’s coupling potential. We group topologically equivalent potential energy curves in phase diagrams for a manifold of simple two-state models. We also illustrate the method’s implementation in a fully quantum-mechanical approach by considering two diabatic states in the radical HBN⇄BNH isomerization. To ensure diabaticity, these states are built on a grid of floating Gaussian orbitals and the potential energy curves are constructed by moving the nuclei.enDiabatic functionsPotential energy surfacesExternal fieldsSemi-classical modelsThesis