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

Abstract

AbstractA 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.