Self-Consistent Component Increment Theory for Predicting Enthalpy of Formation.

The gas-phase enthalpy of formation (ΔHf) plays a fundamental role in predicting reaction thermodynamics and constructing kinetic models. With advances in computational power and method development, chemically accurate quantum chemistry methods that can predict ΔHf values for small molecules are available; however, large molecules are still out of reach. Increment theories provide a means of extending the prediction capability of high-level methods by decomposing the molecular ΔHf into the additive contributions from individual atoms, bonds, groups, or components. Here, we introduce a novel component increment theory, topology-automated force-field interaction component increment theory (TCIT), in which all component contributions are derived exclusively from Gaussian-4 (G4) results for algorithmically generated model compounds. In a benchmark evaluation of noncyclic compounds from the Pedley, Naylor, and Kline experimental ΔHf dataset, TCIT exhibits consistently lower signed and absolute errors compared with the conventional Benson group increment theory (BGIT). These results pave the way for future extensions of TCIT to ring-containing, ionic, and radical species for which experimental data scarcity currently limits the application of BGIT.