Interaction components in the hydrogen halide dications

We have theoretically investigated the interatomic interaction in the low-lying states of HX2+ dications (X = F, Cl, Br, I) by combining results from semiempirical method with ab initio calculations. Main targets have been the complete characterization of the dependence of the charge transfer on the internuclear distance and on the nature of X atom, together with the assessment of its role with respect to other interaction components. The present analysis accounts for differences in the experimental findings related to the features of the permitted bound levels, which are lacking in HF2+ and increase in number and stability on going towards HI2+.