Dramatic relativistic effects in atomization energy and volatility of the superheavy Hassium tetroxide and OsO_4

摘要

Ab initio all-electron relativistic Diract-Fock (KF) and nonrelativistic (NR) Hartree-Fock (HF) self-consistent field (SCF) molecular calculations are rported for the tetrahedral superheavy hassium tetroxide (HsO_4) and its lighter congener OsO_4 at various M-O (M=Hs, Os) bond lengths. Our relativistic DF and NR HF wave functions preddict the ground state of the tetrahedral HsO_4 and OsO_4 to be bound and the predicted relativistic (nonrelativjistic) atomization energy (A_e) for HsO_4 and OsO_4 is 15.35 (6.83) and 10.32 (5.59) eV, respectively. Relativistic effects lead to dramatic increase of approx 225% and 85% in the predicted A_e of HsO_4 and OsO_4, repsctively. Mulliken population analysis of our relativistic DF (NR HF) wave functions for the HsO_4 and OsO_4 yields a charge on Hs of +1.06 (+1.14) and Os of +0.88 (+1.94), respectively. Our DF SCF wave function, in contrast to our NR HF wave function, predicts HsO_4 to be more ionic, i.e., less volatile than OsO_4 and our prediction is in agreement with the recent experiental work for the superheavy element hassium(http://enews.lbl.gov/Science-Articles/Archive/108-chemistry.html, dated 4 June 2001).