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A fully relativistic Dirac–Hartree–Fock and second-order Mo/ller–Plesset study of the lanthanide and actinide contraction

1998; American Institute of Physics; Volume: 109; Issue: 24 Linguagem: Inglês

10.1063/1.477686

1520-9032

Jon K. Laerdahl, Knut Fægri, Lucas Visscher, Trond Saue,

Inorganic Fluorides and Related Compounds

Fully relativistic four-component self-consistent field and correlated calculations at the Mo/ller–Plesset second-order perturbation theory level (MP2) have been performed for the monofluorides and mono- and trihydrides of lanthanum, lutetium, actinium, and lawrencium. The calculated spectroscopic constants are in good agreement with available experimental data. The calculated bond lengths have been compared with values from nonrelativistic calculations to give an estimate of the effect of relativity on the molecular lanthanide and actinide contraction. The calculated lanthanide contraction at the relativistic MP2 level is 0.12, 0.12, and 0.19 Å for the monohydrides, monofluorides, and trihydrides, respectively. The corresponding results for the actinides are 0.20, 0.15, and 0.28 Å, and we demonstrate that the larger size of the actinide contraction is a consequence of relativistic effects. Between 10% and 30% of the lanthanide contraction and between 40% and 50% of the actinide contraction is caused by relativity in these compounds.