Relativistic computational materials science
The general scientific interests of Prof. Kenneth Ruud include the development and application of analytic methods for thecalculation of linear and nonlinear molecular properties, with a particular emphasis on properties involvingmagnetic and/or geometric perturbations. Of particular interesthas been open-ended schemes for studying high-order nonlinear optical processes in the electronic and vibrational frequency domains. Closely linked to this is activity has been the development of methods for describing solvent effectsusing both polarizable continuum methods and polarizable force fields. We have recently implemented real-time methods for propagating the electron density, where a particular novelty has been the extension of this approach tothe two- and four-component relativistic density-functional theory level.Recently, our work on two- and four-component relativistic density-functional theory has been extended to the study of solids using Gaussian basis functions with periodic boundary conditions applied.
We are seeking candidates with an interest indeveloping and applying electronic-structure methods in computational materials science, in particular relativistic, all-electron, four-component density-functional theory using Gaussian basis sets with periodic boundary conditions.We are particularly interested in studying the importance of spin-orbit effects for the properties of topological insulators and for spintronics. The development of methods for studying core-electron properties of solids using either real-time methods or coupled-perturbed Kohn--Sham methods is also of interest, for instance for the study of X-ray absorption spectroscopy or nuclear magnetic resonance spectroscopy.
The exact project description will be developed in collaboration with the MSCA-IF applicant who will have significant influence on the final project description. Although we are primarily seeking candidates with a background in and an interest for computational materials science, candidates primarily interested in relativistic effects in molecules are also encouraged to apply, in particular for the study of molecular response properties.
Motivation
The world around us is relativistic. Highly active research areas such as topologicalinsulators and spintronics originate from spin–orbit effects on the band structure of solid-state materials.Relativity can also have dramatic effects on both X-ray and nuclear magnetic resonance spectra
of solids. Nevertheless, relativistic effects are often ignored or approximated in computational studiesof solids.
Our goal is to fill the gap that currently exists in the treatment of relativity in computational
materials science. We aim to do this by developing accurate, all-electron, two- and four-component relativisticdensity-functional theories (DFT) for periodic systems using both Gaussian-type orbitalsand multiwavelets. The use of multiwavelets will allow us to calculate relativistic DFT for periodicsystems without basis-set errors, providing invaluable benchmark results against which approximaterelativistic and solid-state schemes can be tested. The Gaussian orbital approach will provide a uniqueand efficient toolbox for fully relativistic calculations of band structures and properties of solids.
We believe the methodologies developed will lead to a significant advancement in the accuracyand predictive power that can be obtained from computational studies of relativistic effects on
the band structure of solids. This approach will also provide new and unique tools to study a wide
range of solid-state spectroscopies, such as Mössbauer, nuclear magnetic resonance and X-ray spectroscopy. These spectroscopies probe the electron density close to the nuclei, where relativistic effects can be expected to be the largest. At the same time, the core electrons are often treated in an approximate manner in conventional computational solid-state codes based on the use of pseudopotentials and plane waves. We seek to fill this gap, providing methods that in an accurate manner account for relativistic effects on the electron density on solids, in particular for the core-electron density.
One of the most exciting areas in modern solid-state physics is the quest for two-dimensional
topological insulators. Topological insulators are materials in which the bulk is insulating, withthe Fermi level within the band gap between the conduction and valence bands, whereas the surface states are conducting. In two-dimensional magnetic materials, the spin–orbitinteraction is key to the properties of the topological insulator. In order to design two-dimensionaltopological insulators, there is therefore a need for accurate and reliable prediction of the spin-orbitcoupling in the band structure of these materials, and in particular for understanding the structuralcharacteristics that maximize spin–orbit coupling. Weaim at delivering novel methodologies that will increase the level of accuracy in themodeling of topological insulators. This can lead to significant advances in the search for topologicalinsulators as building blocks in spintronics, where the spin of the electrons rather than the chargeis used for transport. Spintronics holds great promise for major technological advances in datastorage, superconductivity and quantum computing.
Research environment
The Hylleraas Centre for Quantum Molecular Sciences ( which is the acting unit from the University of Tromsø – The Arctic University of Norway, is a Norwegian Centre of Excellence (CoE) established in 2017 by the Research Council of Norway for a period of 10 years, and is one of 23 such CoEs in Norway. The leader of the research centreis Prof. Trygve Helgaker from the University of Oslo until 2022, when Prof. Kenneth Ruud will take over the position as director of the centre. The Hylleraas centre is shared equally between the Universities of Tromsø and Oslo, but the position will be affiliated with the CTCC activities in Tromsø. At the Hylleraas centre in Tromsø, there are 8 permanent researchers/faculty members, 10 postdocs and 5 PhD students. The centre has a full-time administrative officer. The activities of the centre are described in more details on the centre web pages: