No abstract

Many-body potentials up to fourth order are constructed using nonrelativistic, scalar-relativistic, and relativistic coupled-cluster theory to accurately describe the interaction between superheavy oganesson atoms. The obtained distance-dependent energy values were fitted to extended two-body Lennard-Jones and three-body Axilrod− Teller−Muto potentials, with the fourth-order term treated through a classical long-range Drude dipole interaction model. From these interaction potentials, spectroscopic constants for the oganesson dimer and solid-state properties were obtained. Furthermore, these high-level results are compared to scalarrelativistic and two-component plane-wave DFT calculations based on a tailor-made projector augmented wave pseudopotential (PAW-PP) and newly derived parameters for Grimme's dispersion correction. It is shown that the functionals PBE-D3(BJ), PBEsol, and in particular SCAN provide excellent agreement with the many-body reference for solid oganesson. Finally, the results for oganesson are compared and related to the lighter rare gas elements, and periodic trends are discussed.

The chemical nature and aggregate state of superheavy copernicium (Cn) have been subject of speculation for many years.W hile strong relativistic effects render Cn chemically inert, which led Pitzer to suggest an oble-gas-like behavior in 1975, Eichler and co-workers in 2008 reported substantial interactions with ag old surface in atom-at-a-time experiments,s uggesting am etallic character and as olid aggregate state.H erein, we explore the physicochemical properties of Cn by means of first-principles free-energy calculations,w hichc onfirm Pitzerso riginal hypothesis:W ith predicted melting and boiling points of 283 AE 11 Ka nd 340 AE 10 K, Cn is indeed avolatile liquid and exhibits adensity very similar to that of mercury.H owever,i ns tark contrast to mercury and the lighter Group 12 metals,wefind bulk Cn to be bound by dispersion and to exhibit alarge band gap of 6.4 eV, which is consistent with an oble-gas-like character.T his nongroup-conforming behavior is eventually traced backtostrong scalar-relativistic effects,a nd in the non-relativistic limit, Cn appears as ac ommon Group 12 metal.Supportinginformation and the ORCID identification number(s) for the author(s) of this article can be found under: https://doi.org/10.

The normal boiling point (NBP) is a fundamental property of liquids and marks the intersection of the Gibbs energies of the liquid and the gas phase at ambient pressure. This...

State-of-the-art relativistic coupled-cluster theory is used to construct many-body potentials for the noble-gas element radon to determine its bulk properties including the solid-to-liquid phase transition from parallel tempering Monte Carlo simulations through either direct sampling of the bulk or from a finite cluster approach. The calculated melting temperature are 200(3) K and 200(6) K from bulk simulations and from extrapolation of finite cluster values, respectively. This is in excellent agreement with the often debated (but widely cited) and only available value of 202 K, dating back to measurements by Gray and Ramsay in 1909.

Oganesson (Og) is the most recent addition to Group 18. Investigations of its atomic electronic structure have unraveled a tremendous impact of relativistic effects, raising the question whether the heaviest noble gas lives up to its position in the periodic table. To address the issue, we explore the electronic structure of bulk Og by means of relativistic Kohn–Sham density functional theory and many‐body perturbation theory in the form of the GW method. Calculating the band structure of the noble‐gas solids from Ne to Og, we demonstrate excellent agreement for the band gaps of the experimentally known solids from Ne to Xe and provide values of 7.1 eV and 1.5 eV for the unknown solids of Rn and Og. While this is in line with periodic trends for Rn, the band gap of Og completely breaks with these trends. The surprisingly small band gap of Og moreover means that, in stark contrast to all other noble‐gas solids, the solid form of Og is a semiconductor.

Analytical formulas are derived for the zero-point vibrational energy and anharmonicity corrections of the cohesive energy and the mode Grüneisen parameter within the Einstein model for the cubic lattices (sc, bcc, and fcc) and for the hexagonal close-packed structure. This extends the work done by Lennard-Jones and Ingham in 1924, Corner in 1939, and Wallace in 1965. The formulas are based on the description of two-body energy contributions by an inverse power expansion (extended Lennard-Jones potential). These make use of three-dimensional lattice sums, which can be transformed to fast converging series and accurately determined by various expansion techniques. We apply these new lattice sum expressions to the rare gas solids and discuss associated critical points. The derived formulas give qualitative but nevertheless deep insight into vibrational effects in solids from the lightest (helium) to the heaviest rare gas element (oganesson), both presenting special cases because of strong quantum effects for the former and strong relativistic effects for the latter.

The chemical nature and aggregate state of superheavy copernicium (Cn) have been subject of speculation for many years.W hile strong relativistic effects render Cn chemically inert, which led Pitzer to suggest an oble-gas-like behavior in 1975, Eichler and co-workers in 2008 reported substantial interactions with ag old surface in atom-at-a-time experiments,s uggesting am etallic character and as olid aggregate state.H erein, we explore the physicochemical properties of Cn by means of first-principles free-energy calculations,w hichc onfirm Pitzerso riginal hypothesis:W ith predicted melting and boiling points of 283 AE 11 Ka nd 340 AE 10 K, Cn is indeed avolatile liquid and exhibits adensity very similar to that of mercury.H owever,i ns tark contrast to mercury and the lighter Group 12 metals,wefind bulk Cn to be bound by dispersion and to exhibit alarge band gap of 6.4 eV, which is consistent with an oble-gas-like character.T his nongroup-conforming behavior is eventually traced backtostrong scalar-relativistic effects,a nd in the non-relativistic limit, Cn appears as ac ommon Group 12 metal.Supportinginformation and the ORCID identification number(s) for the author(s) of this article can be found under: https://doi.org/10.