Toru Shiozaki of Northwestern University is supported by a CAREER award from the Chemical Theory, Models and Computational Methods program in the Chemistry division to develop novel wave function theories and efficient computer programs for accurately simulating magnetic properties of lanthanide and actinide complexes. The Computational and Data-Enabled Science and Engineering program in the Advanced Cyber Infrastructure division is contributing in part to this award. The Shiozaki group develops multi-configuration electronic structure methods on the basis of the fully relativistic Dirac equation to account for large spin-orbit and spin-spin interactions and quasi-degenerate electronic structure in f-element complexes. These theories are implemented into efficient parallel computer programs, realizing the quantitative simulation of magnetic properties, such as zero-field splitting and electron paramagnetic resonance parameters, of complexes containing 100 atoms or more. The program package developed by the Shiozaki group, BAGEL, is freely available under the GNU General Public License to end users and other researchers.
Einstein's theory of relativity plays a central role in magnetic properties of molecular systems, because the sources of magnetic anisotropy, the spin-orbit and spin-spin couplings, originate from relativity. In the relativistic framework, the behavior of the electrons is governed by the so-called Dirac equation. This work develops theory, algorithms, and computer programs that are tailored to the electronic structure of magnetic molecules to efficiently solve the Dirac equation. The computational tools developed in this work help to rationally design magnetic materials. The computer package resulting from this research is freely available to the community.