Ab Initio Potential Energy Curve for CH Bond Dissociation in Methane

Ab initio calculations on CH4 → CH3 + H were performed at the MP4/6-31G** level including all single, double triple and quadruple excitations. Although triple excitations have little effect on the dissociation energy, they are very important in the 2–3 Å range. The potential curve appears to rise more sharply than a Morse curve in this region. Correlation effects are not important for the HCH angle optimization