Ab initio all-electron fully relativistic Dirac–Fock–Breit calculations for molecules of the superheavy transactinide elements: Rutherfordium tetrachloride

Ab initio all-electron fully relativistic molecular spinor (RMS) Dirac–Fock (DF) self-consistent field (SCF) and nonrelativistic limit Hartree–Fock (HF) calculations are reported at four Rf–Cl bond distances for the ground state of tetrahedral ${\mathrm{(T}}_d)$ rutherfordium tetrachloride $({\mathrm{RfCl}}_{\mathrm{4}})$ with our universal Gaussian basis set. The optimized Rf–Cl bond distance computed from our relativistic and nonrelativistic SCF wave functions for ${\mathrm{RfCl}}_{\mathrm{4}}$ ${\mathrm{(T}}_d)$ is 2.39 and 2.45 Å, respectively. The relativistic correction to the total electronic energy of ${\mathrm{RfCl}}_{\mathrm{4}}$ was calculated as ∼−4355 hartrees (−118 504 eV) at the Dirac–Fock level. The dominant magnetic part of the Breit interaction correction for ${\mathrm{RfCl}}_{\mathrm{4}}$ is estimated by perturbation method as 66.8509 hartrees. Our Hartree–Fock, Dirac–Fock, and Dirac–Fock–Breit calculations predict the tetrahedral ${\mathrm{RfCl}}_{\mathrm{4}}$ to be bound with the calculated dissociation energy of −14.14, −15.56, and −15.53 eV, respectively. Mulliken population analysis of our Dirac–Fock wave function indicates ${\mathrm{RfCl}}_{\mathrm{4}}$ ${\mathrm{(T}}_d)$ to be more volatile than that estimated from the corresponding Hartree–Fock wave function.