Accurate Prediction of Heats of Formation by a Combined Method of B3LYP and Neural Network Correction

Recently, we proposed the XI method which combines the B3LYP/6-311+G(3df,2p)//B3LYP/6-311+G(d,p) method with a neural network correction for an accurate yet efficient prediction of heats of formation (Wu and Xu, J Chem Phys 2007, 127, 214105). In this contribution, we discuss in detail how to set up the X I neural network. We give examples, showing how to apply the XI method and how the applicability of XI can be extended. The overall mean absolute deviation of the XI method from experiment for the 488 heats of fort-nation is 1.52 kcal/mol compared with 9.44 kcal/mol for the original B3LYP results. (C) 2008 Wiley Periodicals, Inc. J Comput Chem 30: 1424-1444, 2009