Polar di-halogen molecules solvated in bosonic helium clusters: The paradigm of ICl(X)

Abstract

Energies and structures of 4He(N)-ICl(X) complexes, N ≤ 30, are determined within the framework of a recently developed Hartree-like approach [Phys. Rev. A 71, 033203 (2005)], in which the He atoms play the role of the electrons and the I and Cl atoms play the role of the nuclei. The potential energy of the system is represented as a sum of the He-ICl triatomic and He-He pair interactions fitted to results of ab initio calculations. The validity of the approach is evaluated through comparisons with the results of "exact" variational calculations performed for the cases of N=1 and 2. The procedure, which furnishes also the wavefunctions, allows for simulation of the infrared spectra of the ICl molecule embedded in the bath of He(N) clusters. Similarly to the case of the "bare" ICl, when the clusters are formed from bosonic He atoms the absorption selection rules lead only to the P and R branches of the spectra (the Q branches are missing). The spectra exhibit a monotonically increasing blueshift, albeit with a decreasing rate, as the cluster size increases.