Dramatic relativistic and magnetic Breit effects for the superheavy reaction Og + 3Ts2 → OgTs6: prediction of atomization energy and the existence of the superheavy octahedral oganesson hexatennesside OgTs6

Our gargantuan ab initio all-electron fully relativistic Dirac–Fock (DF), nonrelativistic (NR) Hartree–Fock (HF) and Dirac–Fock-Breit-Gaunt (DFBG) molecular SCF calculations for the superheavy octahedral oganesson hexatenniside OgTs6 predict atomization energies (AEs) of 9.49, −5.54 and 9.37 eV, at the optimized Og-Ts bond distances of 3.35, 3.44 and 3.36 A, respectively. There are dramatic effects of relativity for the atomization energy for OgTs6 (with seven superheavy atoms and 820 electrons) of ~15.0 eV at both the DF and DFBG levels of theory. Our calculated energies of reaction for the superheavy reaction Og + 3Ts2 → OgTs6 at the NR, DF and DFBG levels of the theory are exoergic by 8.81, 6.33 and 6.26 eV, respectively. The contribution to dispersion interactions increases the DFBG reaction energy for Og + 3Ts2 → OgTs6 by 0.94–7.20 eV. The AEs of OgTs6 to form Og + 6Ts are calculated to be −5.54 at the NR level of theory (that is, OgTs6 is unstable relative to the sum of the NR energies of its constituent atoms) and 9.49 and 9.37 eV at the DF and DFBG levels of theory, respectively. Dispersion interactions increase the AE(DFBG) by 1.30–10.67 eV. Ours are the first dispersion interaction corrected calculations for OgTs6 with seven superheavy atoms and 820 electrons. Mulliken population analysis (MPA) as implemented in the DIRAC code for our DF and NR calculations (using the dyall.cv4z basis) yields the charges Og+0.60 and Og+0.96, respectively, on the central Og atom indicating that our relativistic DF calculations predict octahedral OgTs6 to be less ionic compared to our NR HF calculations. However, due caution must be used to interpret the results of MPA, which are highly basis set dependent.