Critical test of performance of B3LYP functional for prediction of gas-phase acidities and basicities

The gas-phase acidities and basicities for 49 acids and 32 bases, calculate d using B3LYP hybrid DFT method and 6-31G*, 6-31+G*, 6-311+G**, and 6-311+G (3df,3pd) basis sets are compared with corresponding experimental values. T he best results were obtained with 6-311+G(3df,3pd) basis set; the average absolute errors were below 2.5 kcal/mol both for basicities and acidities. Good results for both acidities and basicities (the average absolute errors were less than or equal to 3 kcal/mol) were also obtained using the 6-311G** basis set and even with a moderate 6-31+G* basis set (mean absolute err ors were < 4.6 kcal/mol). The obtained results can be further improved by a pplying empirical corrections. (C) 2000 Elsevier Science B.V. All rights re served.