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

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.