Following his Trial Lecture on “Simulating the electronic structure of molecules under high pressures”, Dr. Kristiansen defended his PhD thesis in a hybrid way (both digitally and physically with a limited number of attendance). The evaluation committee consisted of Prof. Dage Sundholm, University of Helsinki (opponent 1), PD Dr. Florian Bischoff, Humboldt University of Berlin (opponent 2), and Dr. Magnus Ringholm, UiT The Arctic University of Norway (committee leader). The leader of the public defence was Prof. Annette Bayer, Instituttleder for Institutt for Kjemi, NT fakultet, UiT The Arctic University of Norway.
Dr. Brakestad's work was supervised by Professor Kathrin H. Hopmann (lead supervisor), Førsteamanuensis Ingar Leiros, Professor Bjørn Olav Brandsdal, and Professor Luca Frediani.
Popular scientific abstract:
Quantum chemistry as a field was born in the wake of the quantum revolution in the early 1900s, and its goal is to use the laws of quantum mechanics to develop tools that can answer relevant problems in chemistry. A quantum theory of chemistry becomes very complicated as soon as more than two particles are involved, and much of the research tries to come up with good approximations that are both fast and accurate. At the Hylleraas Centre for Quantum Molecular Sciences, a new type of quantum chemistry code has been developed during the last decade, that is able to provide more accurate results compared to conventional methods. In this thesis, I have been testing how good conventional methods are by comparing to our reference method. I have also been implementing algorithms based on Einstein's theory of special relativity, so that very heavy elements can be studied with more accuracy. Our data can be used to help other researchers in rational choice of computational protocols, and guide future development within quantum chemistry.