Naslov
CASSCF/CASPT2 study of mechanism and kinetics of the gas-phase ozone additions to ethene, fluoroethene and chloroethene

Autori
Ljubić, Ivan ; Sabljić, Aleksandar

Vrsta, podvrsta i kategorija rada
Sažeci sa skupova, sažetak, znanstveni

Izvornik
Brijuni conference: Matter Under Extreme Conditions ; BOOK OF ABSTRACTS / Bosanac, Danko S. - Zagreb : Institut Ruđer Bošković, 2004

Skup
IX Brijuni conference: Matter Under Extreme Conditions

Mjesto i datum
Brijuni, Hrvatska, 30.08.2004. - 03.09.2004

Vrsta sudjelovanja
Poster

Vrsta recenzije
Nije recenziran

Ključne riječi
quantum chemistry; CASSCF; CASPT2; multireference methods; ozone; ethene; fluoroethene; chloroethene; mechanism; kinetics; atmospheric chemistry

Sažetak
Studies into reactivity of ozone towards ethene and its monohalogenated derivatives play an important role in evaluating the persistance of these widespread class of pollutants in the troposphere. Multiconfigurational and multireference CASSCF and CASPT2 quantum chemical methods were used in studying mechanism and kinetics of the gas-phase ozone additions to ethene, fluoroethene and chloroethene. Geometrical structures and harmonic vibrational wavenumbers of the reactants, transition states and products were calculated at the CASSCF/cc-pVTZ level of theory. All the electron energies were further refined at the CASPT2/cc-pVTZ level with the optimized CASSCF wave functions taken as the zeroth order. The rate constants and Arrhenius kinetic parameters were then calculated in terms of the conventional transition state theory (C-TST). The overall reliability of the CASPT2 approach was tested by performing a numerical calculation of the equilibrium geometry, harmonic vibrational wavenumbers and anharmonic force field of the ground state ozone. Use of the Dunning's correlation consistent basis sets enabled a two-point extrapolation of the examined properties to the limit of infinite basis. The mechanism of ozonolyses includes formation of the primary addition products, their decomposition and possible re-arrangement to the secondary addition products in condensed phase. Also studied was the unimolecular decomposition of (halo)carbonyl oxides, ozonolytic fragments relevant to the processes in the atmosphere.

Izvorni jezik
Engleski

Znanstvena područja
Kemija

POVEZANOST RADA