Um estudo teórico da reação do radical hidroxila com metanol

Abstract

The use of alcohol as fuel has been considered a promising source of renewable energy. Considerable attention has been given to the reactions of methanol, since it is an important alternative fuel. In this dissertation, firstly it was studied molecular systems involving the reaction between methanol and the hydroxyl radical, optimizing the geometries involved in different theoretical levels like Density Functional Theory (DFT), Hartree Fock (HF) end Coupled Cluster (CCSD(T)) calculated by MOLPRO [1] . From these results it were built energy graphics that characterize the potential energy surface which is not analytical. We used standard methods to study the dynamics of chemical reactions, generating initial conditions by Quasiclassical Trajetory (QCT) method, passing to the study of trajectories on-the-fly, which has a very high computational cost invalidating a statistical study of reaction rates . Thereafter, the procedures to calculate the rate constants on the basis of theoretical molecular properties has been investigated using the fundamental assumption that the profile of the reaction can be described in a theoretical level by The Theory of State Transition (TST) using- to this the kcvt program [28]. We obtained the optimized geometries, the energy graphs of all the points of the reactions OH+CH3OH→H2O+CH2OH and OH+CH3OH→+H2OCH3O in the DFT-BHLYP, HFandCCSD(T)levels, as well as the canonical rates constants for a temperature range from 120K to 3000K.