Ab initio and density functional theory study of the cyanide radical hydrogen abstraction from hydrogen molecules

The transition state structure for the H-2 + CN reaction was generated with the HF, MP2, and HFB computational methods. Because the reaction is highly exothermic, has low activation barrier and an open shell electron system, it presents a difficult computational problem. This system was evaluated by several ab initio methods (HF, MP2, MP3, MP4, QCISD, G1, G2, and G2MP2) and Density Functional Theory (DEF) methods. The computed data was compared with the experimental value and appropriate methods (G1, G2, G2MP2, and HFB) for computing this and similar systems were suggested. (C) 1998 Elsevier Science B.V.