Banca de DEFESA: VITOCLEY BEZERRA DE MORAES
Uma banca de DEFESA de DOUTORADO foi cadastrada pelo programa.STUDENT : VITOCLEY BEZERRA DE MORAES
DATE: 29/02/2024
TIME: 14:00
LOCAL: Ambiente virtural Google Meet
TITLE:
DYNAMICS OF CHEMICAL REACTIONS: THE IMPORTANCE OFMOLECULAR SCALE IN ELUCIDATION OF MECHANISMS
KEY WORDS:
BOMD, DFT, dynamics, PEP, energy flow, mechanism, CP, IRC, SN2.
PAGES: 120
BIG AREA: Ciências Exatas e da Terra
AREA: Química
SUBÁREA: Físico-Química
SPECIALTY: Cinética Química e Catálise
SUMMARY:
Mechanisms of bimolecular reactions in the gas phase can be studied from the perspective of theoretical and computational chemistry through the static methodology that uses the energetics of potential energy profiles together with statistical theories (TST and RRKM) to analyze and interpret the reaction channels and through of Born-Oppenheimer molecular dynamics (BOMD) via simulation of quasi-classical trajectories. The electronic structure methods employed were those based on the second-order Møller-Plesset perturbation theory (MP2), for the description of PEP in the SN2 reaction, and on the density functional theory (DFT), with the hybrid double functional B2PLYP to simulate dynamics trajectories, aiming to investigate the thermal, isotopic and dipole orientation effects. For both approaches, a basis set of Pople were used. For the thermal and isotopic effect, the studied system was , in which a post-TS - sampling was performed; while for the purpose of dipole orientation, we started with isolated reactants. For investigations of the thermal effect, the temperatures sampled were from 300 to 1000 K, and 800 dynamic trajectories were calculated, which sought to evaluate the energy flow of the rotational modes of the system, since, in previous studies, it was verified that the incapacity of the system following an IRC path arises from the vibrational periods for the bending of the mode, implying little rotational energy in the HXCH3 fragments. In this sense, the influence of temperature on roto-vibrational coupling was investigated. The preliminary results point to a weakening of this coupling at higher temperatures, consequently, a smaller number of trajectories that lead to the formation of a product complex (CP), which is classified as an IRC (Intrinsic Reaction Coordinate) trajectory. In the isotopic effect, 8 systems were studied with 100 trajectories for each system, totaling 800 dynamic trajectories. In this step, we intend to investigate whether isotopic systems of greater mass make the bending of the mode slower to obtain more time needed to change the angle (180° to 80°) in order to make the formation of the hydrogen bond that configures the characteristic CP of an IRC behavior is adequate. Additionally, 2700 dipole orientation trajectories, which started from three different orientations (0°, 90° and 180°) of the dipole along the axis. Results of the isotopic effect and dipole orientation are still under analysis.
COMMITTEE MEMBERS:
Interno - JOAO RUFINO DE FREITAS FILHO
Interna - MONICA FREIRE BELIAN
Externo ao Programa - 1753889 - EDUARDO DE CASTRO AGUIAR - UFRPEExterno ao Programa - 2298667 - HELCIO JOSE BATISTA - UFRPEExterna à Instituição - JULIANA ANGEIRAS BATISTA DA SILVA - UFPE