An evaluation of the performance of density functional theory, MP2, MP4, F4, G2(MP2) and G2 procedures in predicting gas-phase proton affinities

✍ Scribed by Brian J. Smith; Leo Radom

• Publisher: Elsevier Science
• Year: 1994
• Tongue: English
• Weight: 590 KB
• Volume: 231
• Category: Article
• ISSN: 0009-2614
• DOI: 10.1016/0009-2614(94)01273-3

✦ Synopsis

The performance of a variety of procedures in calculating gas-phase proton affinities has been assessed. Methods examined include density functional theory with the B-LYP and Becke3-LYP non-local functionals, second-order (MP2) and fourth-order (MP4) Moller-Plesset and fourth-order Feenberg (F4) theories, quadratic configuration interaction (QClSD( T) ), G2 (MP2) and G2. The MP4, F4 and QCISD(T) proton affinities when calculated with the 6-31 lG(d, p) basis set are not in good agreement with experiment, largely reflecting basis set inadequacies. On the other hand, excellent results are obtained with these procedures, and with G2 (MP2 ) and G2, when the 6-3 1 1 + G (3df, 2p) basis set is employed. The DFT procedures are computationally efficient and generally perform reasonably well but occasionally show large errors. Support is presented for the recent suggestion, based on G2 calculations, of a downward revision in the proton affinity of isobutene.