The recent surge in biofuel research due to its long-term economic and environmental benefits has resulted in a deep interest in computational modeling of their relevant combustion properties. Biodiesel, an inherent mixture of methyl esters of long fatty acids like palmitic acid and stearic acid, generates a range of intermediates and products on combustion. The steep scaling of highly accurate methods on large molecules makes direct computations on such systems intractable, prohibiting an exhaustive study. Herein we apply our connectivity based-hierarchy (CBH) in conjunction with DFT methods to determine accurate bond dissociation energies (BDEs) of various C–C and C–H bonds in biofuel molecules. CBH comprises of well-defined and reliable error cancellation schemes deriving accurate enthalpies of formation of both <i>open </i>and <i>closed </i>shell organic molecules at modest computational cost. We evaluate the performance of different DFT methods using a test-set of 18 reactions involving various C–C and C–H bond dissociations in. smaller systems such as methyl butanoate by calibration against values calculated with more rigorous multi-reference methods. The CBH-2 corrections for several dispersion corrected (D3) functionals result in mean absolute errors of &lt; 1.5 kcal/mol. The present protocol has been applied to derive accurate BDEs of large molecules like methyl linoleate and methyl stearate.

Connectivity-based hierarchy to eliminate systematic errors: Accurate combustion properties of biofuel molecules using DFT

253rd National Meeting (2017)

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