Chemical reaction dynamics and potential energy surfaces for hydrogen transfer reactions and large systems.

摘要

The ability of chemists to accurately model chemical reaction dynamics is of central importance for understanding the reactivity of various systems ranging from small molecules in the gas phase to macromolecules, such as enzymes, in liquid solution. This thesis presents theoretical and computational studies in four areas related to chemical reaction dynamics and potential energy surfaces for hydrogen transfer reactions and large systems: (i) gas-phase studies of the reaction of H + CH4 ↔ H2 + CH 3 plus its kinetic isotope effects (KIEs) involving deuterium and muonium; the latter is an ultralight isotope of hydrogen; (ii) benchmark calculations of reaction energies and reaction barrier heights for hydrogen atom transfers between hydrocarbon fragments; (iii) development of a combined quantum mechanical/molecular mechanical (QM/MM) method for proteins and other complex systems with the QM region connected smoothly to the MM region by the generalized hybrid orbital (GHO) method; (iv) development of a highly efficient geometry optimization strategy for large systems by using blocked Hessians.