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An implementation of spināorbit coupling within a two-component generalization of the density functional code MAGIC is described. The spināorbit operator is represented in the effective one-electron mean-field approximation and included into the Fock matrix within an iterative self-consistent scheme. First tests have been carried out for the spināorbit splitting of several atoms. The spināorbit effect on the bond distance and harmonic frequency of some diatomics has also been determined. This scheme allows to include spināorbit in a simple way and can be efficiently used to treat large systems. |
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An implementation of the DouglasKroll (DK) transformation is described within a new relativistic quantum chemistry code, MAGIC, which performs calculations on systems containing heavy atoms. This method reduces the computational cost in terms of memory requirements that are associated with completeness identities in the DK implementation by factorizing the one-electron matrices into smaller ones that depend only on two atoms at a time. Examples are presented. |
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A study on the UF6 monomer and dimer was carried out within the density functional method. The UāF distance in the UF6 monomer was optimized at different levels of theory, pointwise, assuming octahedral geometry, (1) by using an all-electron basis for both U and F in a nonrelativistic calculation; (2) by using a relativistic effective core potential (RECP) on U and nonrelativistic effective core potential (ECP) on the fluorines; and (3) by using RECP on the U atom and an all-electron basis on the F atoms. Atomization energies of 23.11, 33.92, and 35.66 eV were obtained at the three levels, respectively. Relativistic effects lead to about a 50% increase in the atomization energy. For the UF6 dimer, the potential energy curve, as a function of the intermolecular UāU distance, was computed at level 2, and the rotational barrier between the two monomers was determined. Similar calculations were performed on the corresponding PuF6 species. Comparisons are made with experiment and other theoretical studies, where available. |
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An efficient approach for evaluating effective core potential integrals which involve projection operators has been implemented in the MAGIC quantum chemistry program. The methodology is presented and its performance is examined through illustrative calculations on transition metal and actinide compounds. |