Isoelectronic dimers [(XH3)2, (YH2)2, (ZH)2, and (Rg)2] in the groups of the periodic system: ab initio quantum chemical calculations

The (ZH)2, (YH2)2, (XH3)2 and (Rg)2 dimers [Z=F-At; Y=O.Po; X=N, Bi; Rg=rare gas] were studied ab initio using the CCSD(T) and MP2 procedures. Average relativistic effective potentials were used for all the halogens, while Stuttgart effective core potentials were used for the remaining non-hydrogen atoms. All the (HX)2 structure are H-bonded. All the stabilization energies mutually approach when passing down the group of the periodic system.