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Register a new userDirac-Fock-Breit-Gaunt calculations for the reaction Og + 6 CO -> Og(CO)6 or Og(OC)6
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Our all electron (DFBG) calculations show differences between relativistic and non-relativistic calculations for the structure of the isomers of Og(CO)6
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Our all-electron fully relativistic Dirac-Fock (DF) and nonrelativistic (NR) Hartree-Fock (HF) SCF molecular calculations for the superheavy tetrahedral (T$_d$) oganesson tetratennesside OgT$_4$ predict atomization energy (Ae) of 7.45 and -11.21 eV, respectively. Our DF and NR calculations, however for the square planar (D$_{4h}$)OsTs$_4$ predict atomization energy (Ae) o 6.34 and -8.56 ev, respectively. There are dramatic relativistic effects for the atomization energy of T$_d$ and D$_{4h}$ OgT$_4$ of -18.65 eV and 14.90 eV, respectively. Whereas our DF calculations predict the T$_d$OgT$_4$ to be more stable than the D$_{4h}$ OgT$_4$ by ~1.10 eV, our NR calculations predict the D$_{4h}$ OgT$_4$ to be more stable than the T$_d$ OgT$_4$ by ~2.65eV. Our NR calculations predict both the T$_d$ and D$_{4h}$ OgTs$_4$ to be unbound by 11.21 and 8.56 eV, respectively. However our relativistic DF calculations predict both the T$_d$ and D$_{4h}$ OgT$_4$ to be bound by 7.45 and 6.34 eV respectively and so the relativistic treatment is mandatory for bonding and binding in the pentatomic superheavy system with 586 electrons involving the two heaviest SHE Ts and Og.
According to theory, cluster radioactivity becomes an important decay mode in superheavy nuclei. In this work, we predict that the strongly-asymmetric fission, or cluster emission, is in fact the dominant fission channel for $^{294}_{118}$Og$_{176}$, which is currently the heaviest synthetic isotope known. Our theoretical approach incorporates important features of fission dynamics, including quantum tunneling and stochastic dynamics up to scission. We show that, despite appreciable differences in static fission properties such as fission barriers and spontaneous fission lifetimes, the prediction of cluster radioactivity in $^{294}_{118}$Og$_{176}$ is robust with respect to the details of calculations, including the choice of energy density functional, collective inertia, and the strength of the dissipation term.
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 OgTs$_6$ predict atomization energy (Ae) of 9.47, -5.54and 9.37 eV, at the optimized Os-Ts bond distances of 3.35, 3.34 and 3.36 angstroms, respectively. There are dramatic effects of relativity for the atomization energy of OgTs$_6$ (with seven superheavy elements and 820 electrons) of ~ 15.0 eV each at both the DF and DFBG levels of theory, respectively. Our calculated energy of reaction for the titled superheavy reaction Og + 3Ts$_2$ -> OgTs$_6$ at the DF, NR and DFBG levels of theory is 6.33, 8.81, and 6.26 eV, respectively. Mulliken analysis as implemented in the DIRAC code for our DF and NR calculations (using the dyall.ev4z 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 OgTs$_6$ to be less ionic. However, due caution must be used to interpret the results of Mullikens population analysis, which is highly basis set dependent.
Hard magnets with high coercivity, such as Nd2Fe14B and SmCo5 alloys, can maintain magnetisation under a high reverse external magnetic field and have therefore become irreplaceable parts in many practical applications. Molecular magnets are promising alternatives, owing to their precise and designable chemical structures, tuneable functionalities and controllable synthetic methods. Here, we demonstrate that an unusually large coercive field can be achieved in a single-chain magnet. Systematic characterisations, including magnetic susceptibility, heat capacity and neutron diffraction measurements, show that the observed giant coercive field originates from the spin dynamics along the one-dimensional chain of the compound because of the strong exchange coupling between Co(II) centres and radicals.
We investigate the nature of CO emission from z~6 quasars by combining non-LTE radiative transfer calculations with merger-driven models of z~6 quasar formation that arise naturally in LCDM cosmological simulations. We consider four model quasars formed in 10^12-10^13 M_sun halos from different merging histories. Our main results follow. Owing to massive starbursts and funneling of dense gas into the nuclear regions of merging galaxies, the CO is highly excited and the flux density peaks between J=5-8. The CO morphology of z~6 quasars often exhibits multiple emission peaks which arise from H2 concentrations which have not yet fully coalesced. Quasars at z~6 display a large range of sightline dependent line widths such that the lines are narrowest when the rotating H2 gas associated with the quasar is viewed face-on (when L_B is largest), and broadest when the gas is seen edge-on (when L_B is lowest). Thus for all models selection effects exist such that quasars selected for optical luminosity are preferentially face-on which may result in detected CO line widths narrower than the median. The sightline averaged line width is reflective of the circular velocity (V_c) of the host halo, and ranges from sigma~300-650 km/s. For optically selected QSOs, 10-25% (halo-mass dependant) of sightlines have narrow line widths compatible with the sole CO detection at z>6, J1148+5251. When accounting for both the temporal evolution of CO line widths, as well as the redshift evolution of halo V_c, these models self-consistently account for the CO line widths of both z~2 sub-mm galaxies and QSOs. Finally, the dynamical mass derived from the sightline averaged line widths provides a good estimate of the total mass, and allows for a stellar bulge and SMBH consistent with the local M_BH-M_bulge relation. [abridged]
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