Enthalpy of Formation Modeling Using Third Order Group Contribution Technics and Calculation by DFT Method.

Abstract

Recently, with the development of calculators and numerical tools, quantum computations to explore the electronic, structural and dynamic properties of matter without resorting to experimental knowledge have seen increasing development. Thus, it is possible to perform ab-initio calculations with increasing precision and for increasingly larger systems. In the scientific literature, papers using ab-initio quantum computation for the prediction of formation enthalpies is more and more numerous. The aim of this paper is to develop a theoretical method to calculate standard enthalpy of formation in gas stat for organic compounds using group contribution technics (third-order group contribution method). For the establishment of this method, 750 molecules are used. In parallel with group contribution methods, this paper presents another approach to calculate gas-state formation enthalpies based on DFT method. The calculation involved 30 molecules with at least one ring from C3 to C13. Finally, DFT and group contribution results are compared.

Group Contribution Revisited: The Enthalpy of Formation of Organic Compounds with “Chemical Accuracy”

“…It goes without saying that with such a typical number of parameters compared to the number of data points, one cannot be really surprised about a good fit. For the ∆Hf [4,13,17], we also observe very many higher-order parameters. The objective of fitting parameters in a specific model should obviously be to avoid any kind of what is known as overfitting because this seriously deteriorates the quality of the predictive behavior of the method.…”

“…In recent decades, the GC methodology has been developed by various groups of authors and deals with a variety of molecular properties. GC methods include those devised by Joback and Reid [5], Benson and co-workers [6,7], Domalski and Hearing [8], Constantino and Gani [9], Marrero and Gani [10], Rarey et al [11,12], Hukkerikar et al [4] and Kadda et al [13]. One of these properties is gas-phase ∆Hf organic molecules.…”

“…As previously mentioned, in the present work, we will adopt the "group" definition in the sense of van Krevelen and Chermin [14]. This approach is different from the one in other works [4,10,13]. Still, the fact that not all properties can be accounted for quantitatively, sufficiently and accurately using the additivity of these group contributions must be accounted for.…”

Group Contribution Revisited: The Enthalpy of Formation of Organic Compounds with “Chemical Accuracy” Part II

“…[4,6]. ), which was also practiced by Kadda et al [7] (see in particular the Supplementary Material to reference [7]). Adopting this choice leads to benzene consisting of 6 aCH groups.…”

“…[5]: This software module is regularly updated, so individual results may differ from those reported in papers including Refs. [4,6]), which was also practiced by Kadda et al [7] (see in particular the Supplementary Material to reference [7]). Adopting this choice leads to benzene consisting of 6 aCH groups.…”