Relativistic effects on experimentally studied gas-phase properties of the heaviest elements

Abstract

Influence of relativistic effects on atomic properties and volatility of element 112 and its homolog Hg has been studied using results of relativistic atomic and molecular calculations. Volatility was considered as sublimation of macro-amounts or adsorption of single atoms on inert and metal surfaces. For predictions of adsorption on metal (gold) surfaces, fully relativistic and non-relativistic density functional theory calculations were performed for various intermetallic compounds of Hg and element 112: dimers and metal–gold cluster systems. Results show that influence of relativistic effects on volatility is different depending on the process. For element 112 as metal the sublimation enthalpy will be drastically decreased by relativistic effects, so that it will be the most volatile in the group, probably a gas. Upon adsorption on an inert surface, element 112 will have the strongest dispersion interaction with the surface in group 12 and hence will be the least volatile. On the contrary, upon adsorption on transition metal surfaces, e.g., on the (100) surface of gold, element 112 will be more volatile than Hg, though the influence of relativistic effects on the adsorption energy is different depending on the adsorption position. For example, relativistic effects do not increase (or could even decrease) the adsorption energy of element 112 when adsorbed in the on-top position, while for the hollow position, relativistic effects substantially increase the interaction energy, so that relativistically element 112 will be less volatile than non-relativistically. The calculations have shown that the relativistic and non-relativistic properties have opposite trends from Hg to element 112.