An overview on potential energy surfaces of rare-gas dihalogen van der Waals clusters

摘要

In this review we report on interaction potential surface calculations of Rg-XY (Rg = rare gas and X, Y = halogens) van der Waals (vdW) complexes. Experimental data available on the structure and dynamics of such systems mainly originate from the B X excitation spectroscopy and, therefore, potential surfaces for both electronic states involved are required for the theoretical treatments. Hence, ab initio technology is used at the coupled-cluster (CCSD(T)) level of theory for constructing these surfaces. Relativistic effects are included with the use of large-core pseudo-potentials for the halogen atoms, while efficient augmented correlation-consistent polarized basis sets are employed for the Rg ones, to ensure saturation in interaction energies in the highest level of electron correlation treatment. For all ground state Rg-dihalogen systems studied, the potential surface shows minima for both linear and T-shaped orientations. In contrast, the potential surfaces of the electronically B excited state complexes present T-shaped minimum. Variational calculations for both electronic potentials are performed to calculate the bound states of the ground and B excited vdW complexes, and binding energies, vibrationally averaged structures and spectral shifts are determined. Here, an application of the present methodology on the ground X and B excited HeI2 conformers is reported and the obtained results are discussed in terms of available experimental data.