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Accurate Calculations of Rate Constants for the Forward and Reverse H 2 O + CO ↔ HCOOH Reactions
Author(s) -
Vichietti Rafael Mario,
Spada Rene Felipe Keidel,
Silva Albérico Borges Ferreira da,
Machado Francisco Bolivar Correto,
Haiduke Roberto Luiz Andrade
Publication year - 2017
Publication title -
chemistryselect
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.437
H-Index - 34
ISSN - 2365-6549
DOI - 10.1002/slct.201701137
Subject(s) - anharmonicity , extrapolation , coupled cluster , chemistry , reaction rate constant , arrhenius equation , basis set , thermodynamics , excitation , valence (chemistry) , atomic physics , physics , computational chemistry , quantum mechanics , molecule , kinetics , activation energy , density functional theory , mathematics , mathematical analysis , organic chemistry
The forward and reverse H 2 O + CO ↔ HCOOH reactions were investigated using high‐level methodologies in order to provide accurate thermodynamic and kinetic data between 200 and 4000 K. Geometries of reactants, transition state (TS), and product were determined with the Coupled Cluster Theory including single and double excitations (CCSD) along with the cc‐pVTZ basis set, whereas associated vibrational frequencies, zero‐point energies, and thermal corrections were scaled to consider anharmonicity effects. Besides, the description of electronic energies was improved by means of core‐valence correlation and iterative triple‐excitation contributions together with a complete basis set extrapolation ( E CBS,Δ ) in order to achieve accurate values of enthalpies, Gibbs energies, and rate constants. Such rate constants were estimated at the high‐pressure limit by variational TS treatments combined with different quantum tunneling approaches. Finally, modified Arrhenius’ equations were fitted between 700 and 4000 K from our most reliable results.