REACTION ENERGETICS OF TETRAHEDRANE AND OTHER HYDROCARBONS - AB-INITIO AND DENSITY-FUNCTIONAL TREATMENTS

Reaction energetics of the highly strained tetrahedrane molecule, as w ell as some smaller hydrocarbons, were computed at the ab initio MP4, QCISD (T), G1, and G2 levels and also by several density functional (D F) approaches: VWN(LDA), PW86, BLYP, and B3LYP. A variety of basis set s were used in the DF calculations. For atomization processes, nonloca l DF procedures are superior to MP4 and QCI. For the other reactions, B3LYP is the most reliable DF approach and is overall competitive with MP4 and QCISD (T), although the MP4/6-311G(2 df, p) results are gener ally the closest to the experimental and/or the G2 values. There is no consistent correlation between the accuracy of the DF results and the size of the basis set. (C) 1996 John Wiley & Sons, Inc.