Bond additivity corrections for CBS‐QB3 calculated standard enthalpies of formation of H, C, O, N, and S containing species

Abstract

A prerequisite for the generation of detailed fundamental kinetic models is the availability of accurate thermodynamic properties. To address the scarcity of accurate experimental data, theoretical calculations can be used. The accuracy of these quantum chemistry methods for determination of thermodynamic properties can be improved by making use of empirical correction methods, such as the isodesmic bond additivity correction (BAC) method. In this work, ab initio calculations for a set of 371 molecules have been performed to determine a new set of BACs for the CBS‐QB3 level of theory. For each of these molecules also accurate experimental data, that is with an experimental uncertainty less than 3 kJ mol−1, is available. This broad dataset of hydrocarbons and heteroatomic compounds contains (non)cyclic molecules with a wide range of functional groups consisting of hydrogen, carbon, oxygen, nitrogen, and sulfur. The new set of 26 BAC parameters is obtained via linear regression analysis, minimizing the differences between experimental and corrected CBS‐QB3 values. The CBS‐QB3 method combined with BACs succeeds in approximating the experimental standard enthalpy of formation at 298 K with an accuracy of 4 kJ mol−1 for almost all species. The BACs reduce the mean absolute deviation for the complete dataset from 5.65 to 2.37 kJ mol−1, corresponding to a decrease of the root mean square deviation from 6.95 to 3.00 kJ mol−1.

Unimolecular Decomposition of 1,3-Dioxetane and 1,3,5-Trioxane Derivatives: Fast and Accurate Estimation of Kinetic Parameters

“…All other internal modes are represented by a harmonic oscillator approximation. To obtain accurate standard enthalpies of formation, which are determined via the atomization method, two additional corrections, i.e., spin−orbit corrections 39 and bond additivity corrections, 40 are applied. According to Paraskevas et al, 41 chemically accurate, i.e., a maximum deviation of 4 kJ mol −1 , standard enthalpies of formation are obtained using the described methodology.…”

A detailed experimental and kinetic modeling study on pyrolysis and oxidation of oxymethylene ether-2 (OME-2)

“…The atomization method is used to calculate the enthalpy of formation. Two corrections are applied to correct the enthalpy of formation calculated at the CBS-QB3 level of theory for systematic errors, i.e., spin-orbit corrections (SOC) [33] as these are not part of the CBS-QB3 methodology and empirical bond additive corrections (BAC) [34,35]. There is no SOC and BAC contribution applied in case only relative enthalpies are required, i.e., for the calculation of reaction rate coefficients and the construction of potential energy surfaces.…”

The secondary chemistry of synthetic fuel oxymethylene ethers unraveled: Theoretical and kinetic modeling of methoxymethyl formate and formic anhydride decomposition

“…Thermodynamic parameters are derived from the total partition function considering additionally the molecular symmetry and the number of optical isomers (enantiomers). The atomization method is used to calculate the enthalpy of formation at 298 K. The latter is corrected with spin-orbit corrections (SOCs) [23] and empirical bond additive corrections (BACs) [24,25] to account for systematic deviations between the calculated and experimentally measured values. SOCs and BACs are not applied in the case only relative formation enthalpies are required, i.e.,…”