Towards accurate ab initio predictions of the vibrational spectrum of methane

We have carried out extensive ab initio calculations of the electronic structure of methane, and these results are used to compute vibrational energy levels. We include basis set extrapolations, core-valence correlation, relativistic effects, and Born-Oppenheimer breakdown terms in our calculations. Our ab initio predictions of the lowest lying levels are superb. (C) 2002 Published by Elsevier Science B.V.