Three-Dimensional ab initio Potential Energy Surface and Predicted Spectra for the CH₄-Ne Complex

We present a new three-dimensional potential energy surface (PES) for CH _4 -Ne complex. The electronic structure computations were carried out using the coupled-cluster method with singles, doubles, and perturbative triples CCSD(T), the augmented correlation-consistent aug-cc-pVXZ (X = T, Q) basis sets were employed with bond functions placed at the mid-point on the intermolecular axis, and the energies obtained were then extrapolated to the complete basis set limit. Analytic intermolecular PES is obtained by least-squares fitting to the Morse/Long-Range (MLR) potential function form. These fits to 664 points have root-mean-square deviations of 0.042 cm ^-1 . The bound rovibrational levels are calculated for the first time, and the predicted infrared spectra are in good agreement with the experimental values. The microwave spectra for CH _4 -Ne dimer have also been predicted for the first time. The analytic PES can be used for modeling the dynamical behavior in CH _4 -(Ne) _N clusters, and it will be useful for future studies of the collision-induced-absorption for the CH _4 -Ne dimer.