Theoretical study of the He–HCN, Ne–HCN, Ar–HCN, and Kr–HCN complexes

Abstract

The two-dimensional potential energy surfaces for the He–HCN, Ne–HCN, Ar–HCN, and Kr–HCN complexes are presented. Calculations have been performed using single and double excitation coupled-cluster theory with noniterative treatment of triple excitations [CCSD(T)] and the augmented correlation-consistent polarized triple-zeta basis set (aug-cc-pVTZ) with an additional (3s3p2d2f1g) set of bond functions. The potentials have been used to find the vibration–rotation energies of the four complexes and their deuterated analogs. The frequencies of rotational or rovibrational transitions found for He–HCN and Ar–HCN are in very good agreement with the experimental results. Good agreement is also obtained with the experimental rotational transition frequencies for Kr–HCN. For Ne–HCN, on the other hand, the agreement with the experimental data is not as good, but can be improved by using larger basis sets.