Ab initio electronic structure investigation of protonated mixed rare gas dimers [NeHHe]+, [ArHHe]+ and [ArHNe]+

The equilibrium structures and bonding features of [NeHHe]+, [ArHHe]+, and [ArHNe]+ are investigated using correlated ab initio methods and a large number of basis sets. For all the three systems, linear structures with the hydrogen atom in the middle have been found to be the most stable. The bond lengths of argon atoms with hydrogen are shorter than the HeH and NeH bond lengths in [ArHHe]+ and [ArHNe]+, respectively. This leads to the dissociation energies being very large for breaking the heavier rare gas-hydrogen atom bond. In [NeHHe]+, the NeH bond length is larger than HeH length. In addition to the global minima, two other local minima are also located for each of the systems with either of the rare gases in the middle. All the stable geometries are characterized by frequency calculations.