Solving the Density Functional Conundrum: Elimination of Systematic Errors To Derive Accurate Reaction Enthalpies of Complex Organic Reactions.

The failure of available density functional methods to compute accurate reaction enthalpies of common organic reactions is well documented. Herein, we demonstrate that the disparate results from different functionals stem from the systematic errors in the underlying elementary reactions that represent the changes in the bonding environment between reactants and products. We develop a rigorous protocol to correct for these systematic errors and obtain dramatically improved results with deviations of only 1-2 kcal/mol for most functionals.