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The aqueous solvation of the uranylfluoride complex [UO2F42−] was studied using full quantum mechanical (QM) and hybrid QM/molecular mechanics (MM) methods. Inclusion of a complete first solvation shell was found necessary to reproduce the experimentally observed heptacoordination of uranium. An efficient and accurate computational model is proposed that consists of structure optimization of the coordinated uranium complex as QM region, followed by single‐point full QM calculations to compute relative energies. This method is proven feasible for studies of large solvated actinide complexes. © 2003 Wiley Periodicals, Inc. J Comput Chem 25: 386–392, 2004

Various methods for the inclusion of relativistic effects in the calculation of NMR parameters are discussed. Benchmark values for the NMR shieldings and indirect nuclear spin–spin coupling tensors for the hydrogen halides are calculated using the four-component relativistic random phase approximation method. Apart from recovering the well-known trend of increasing hydrogen isotropic shielding going from HF to HI, we also find a large effect on the anisotropy that decreases along this series. Inclusion of spin-orbit coupling in a nonrelativistic formalism suffices to recover both effects on the hydrogen shieldings but fails to reproduce the much larger effect on the halogen shieldings. This effect can be explained by considering the relativistic mass-velocity operator that contains correction terms to the nonrelativistic magnetic field operators. We recommend routine inclusion of the one-electron spin-orbit correction in calculations of hydrogen shieldings for hydrogens bonded to heavy atoms. For the heavy nucleus shielding one should include an additional mass-velocity correction. The relativistic effect on the indirect nuclear spin–spin coupling tensor is large and affects mainly the isotropic values; the effect on the anisotropy is small. ©1999 John Wiley & Sons, Inc. J Comput Chem 20: 1262–1273, 1999

The MOLFDIR package of programs is used to perform fully relativistic all-electron Dirac-Fock and Dirac-Fock-Breit calculations for the the XeFn (n = 1, 2, 4, 6) molecules assuming experimental symmetries. The Xe-F bound length for XeF2, XeF4, and XeF6 is optimized and the total ground-state energies are reported. The variation of the relativistic energy and the Breit correction with the internuclear distance is plotted. The role of relativistic corrections in the proper prediction of the Xe-F distance and the dissociation energy of the molecule is discussed. The problem of the reduction of the number of scalar two-electron integrals is studied. Our results illustrate the possibilities, difficulties, and limitations of the finite basis Dirac-Fock calculations for polyatomic molecules of different symmetries. © 1997 by John Wiley & Sons, Inc.

The MOLFDIR package of programs is used to perform fully relativistic all‐electron Dirac‐Fock and Dirac‐Fock‐Breit calculations for the the XeFn(n= 1, 2, 4, 6) molecules assuming experimental symmetries. The Xe‐F bound length for XeF2, XeF4, and XeF6is optimized and the total ground‐state energies are reported. The variation of the relativistic energy and the Breit correction with the internuclear distance is plotted. The role of relativistic corrections in the proper prediction of the Xe‐F distance and the dissociation energy of the molecule is discussed. The problem of the reduction of the number of scalar two‐electron integrals is studied. Our results illustrate the possibilities, difficulties, and limitations of the finite basis Dirac‐Fock calculations for polyatomic molecules of different symmetries. © 1997 by John Wiley & Sons, Inc.