Ab initio calculations and modeling of diabatic potential energy surfaces for the Van der Waals complex Cl(2P)⋯CH4(X 1A1)

The three lowest potential energy surfaces, Σ, Πx and Πy of the Van der Waals complex Cl(2P)+CH4(X 1A1) are derived from accurate ab initio calculations for the vertex, edge and face geometries. The restricted coupled cluster singles, doubles and non-iterative triples excitations [RCCSD(T)] level of theory is applied with a large basis set. The global Van der Waals minimum, which is 348 cm−1 deep, occurs at R=3.3 Å on the Σ surface and is located in the vicinity of the face arrangement.