Relativistic Hyperfine Interaction in Single-Molecule Magnets: Multiconfigurational Study

Accurate calculations of hyperfine interaction parameters in single molecule magnets are of crucial importance for quantum information applications. Relativistic treatment of hyperfine operators is essential in such calculations especially in the presence of a significant Fermi contact contribution. Here, we describe an implementation of a first-principles computational methodology for magnetic hyperfine and electric quadrupole interactions within the framework of multiconfigurational quantum chemistry methods. The relativistic effects are included based on the Douglas-Kroll-Hess Hamiltonian. Hyperfine interaction parameters are calculated for simple molecules and compared with the literature. The method is then used to study electronic-nuclear spectra and magnetization dynamics in different single molecule magnets. Further, the effect of an external electric field on hyperfine interactions is studied. Conditions necessary for realization of a strong hyperfine Stark effect are discussed.