The generator coordinate Dirac–Fock method for open-shell atomic systems

New and Practical Formulation for Overlaps of Bogoliubov Vacua

In this Letter, we present a new expression for the overlaps of wave functions in Hartree-Fock-Bogoliubov based theories. Starting from the Pfaffian formula by Bertsch et al. [1], an exact and computationally stable formula for overlaps is derived. We illustrate the convenience of this new formulation with a numerical application in the context of the particle-number projection method. This new formula allows for substantially increased precision and versatility in chemical, atomic, and nuclear physics applications, particularly for methods dealing with superfluidity, symmetry restoration, and uses of nonorthogonal many-body basis states.

Dissociation energy of ekaplutonium fluoride E126F: The first diatomic with molecular spinors consisting of g atomic spinors

Our ab initio all-electron fully relativistic Dirac-Fock (DF) and nonrelativistic (NR) Hartree-Fock (HF) self-consistent field (SCF) calculations predict the superheavy diatomic ekaplutonium fluoride E126F to be bound with the calculated dissociation energy of 7.44 and 10.46 eV at the predicted E126-F bond lengths of 2.03 and 2.18 Angstroms, respectively. The antibinding effects of relativity to the dissociation energy of E126F are approximately 3 eV. The predicted dissociation energy with both our NR HF and relativistic DF SCF wave functions is fairly large and is comparable to that for very stable diatomics. This is the first case, where in a diatomic, an atom has g orbital (l = 4) occupied in its ground state electronic configuration and such superheavy diatomics would have occupied molecular spinors (orbitals) consisting of g atomic spinors (orbitals). This opens up a whole new field of chemistry where g atomic spinors (orbitals) may be involved in electronic structure and chemical bonding of systems of superheavy elements with Z> or =122.

Relativistic molecular orbital study of the optical and magnetic properties of hexachloro protactinate (IV): PaCl62−

Our ab initio all-electron Dirac-Fock and the corresponding nonrelativistic limit calculations performed at four Pa-Cl bond distances yield for octahedral PaCl(6) (2-) the optimized Pa-Cl bond distances of 2.758 and 2.771 Angstroms, respectively. Dirac scattered wave and its nonrelativistic limit calculations are performed at the optimized Pa-Cl bond distances using a first-order perturbation procedure to obtain the molecular g and hyperfine tensors for the octahedral anion PaCl(6) (2-). The calculated Zeeman and (231)Pa hyperfine interactions are in fairly good agreement with the electron paramagnetic resonance and electron nuclear double resonance values of the Pa(4+) impurity site in the octahedral Cs(2)ZrCl(6) lattice. The calculated relativistic transition energies of the 5f-->5f and 5f-->6d absorption bands are also in good agreement with the experimental results.

Electronic structure and prediction of atomization energy of naked homoleptic uranium hexacarbonyl U(CO)6

Our ab initio all-electron fully relativistic Dirac-Fock and nonrelativistic Hartree-Fock self-consistent field (SCF) calculations predict the octahedral (Oh) uranium hexacarbonyl U(CO)6 to be bound with the calculated atomization energy of 49.84 and 48.76 eV at the predicted U-C bond lengths (assuming the C-O bond distance fixed at 1.17 A) of 2.53 and 2.63 A, respectively. Moreover, our all-electron fully relativistic Dirac-Fock SCF calculations predict U(CO)6 to be lower in energy by 3.90 eV with respect to dissociation into U plus six CO ligands. We predict U(CO)6 (Oh) to be very stable in view of our predicted large atomization energy (approximately 49 eV) and stability (approximately 4 eV) with respect to dissociation into U plus six CO molecules. Innovative techniques should be devised for the synthesis of uranium hexacarbonyl since the usual synthetic methods have failed so far for this naked actinide hexacarbonyl.