Jon Henriksen Austad

• Austad, Jon; Borgoo, Alex; Tellgren, Erik & Helgaker, Trygve (2020). Bonding in the helium dimer in strong magnetic fields: The role of spin and angular momentum. Physical Chemistry, Chemical Physics - PCCP.  ISSN 1463-9076.  22(41), s 23502- 23521 . doi: 10.1039/d0cp03259j
• Reimann, Sarah; Borgoo, Alex; Austad, Jon; Tellgren, Erik; Teale, Andrew Michael; Helgaker, Trygve & Stopkowicz, Stella (2019). Kohn–Sham energy decomposition for molecules in a magnetic field. Molecular Physics.  ISSN 0026-8976.  117(1), s 97- 109 . doi: 10.1080/00268976.2018.1495849

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• Austad, Jon; Helgaker, Trygve & Tellgren, Erik (2020). Theoretical Investigations of Molecular Electronic Structure in a Magnetic Field. Series of dissertations submitted to the Faculty of Mathematics and Natural Sciences, University of Oslo.. 2295. Fulltekst i vitenarkiv. Vis sammendrag

  Most available literature on molecular systems in magnetic fields are limited to special cases: Either small or highly symmetric species of specific orientation to the field, or fields of low intensity - or combinations of the above. This dissertation is devoted to the development, implementation, calibration, analysis and usage of computational quantum chemistry methods that are freed from such restrictions. Three research papers are presented. One deals with the inner workings of a generalized variant of Density Functional Theory which allows the magnetic field to be directly included (BDFT), and explores in depth how various functionals handle diamagnetic, paramagnetic and aromatic molecules. The second paper investigates the rich chemistry of the helium dimer in a strong magnetic field, thoroughly maps out the electronic structure of the molecule, and presents the many different magnetic bonding mechanisms and interactions that exist in this regime. The final paper revolves around application of highly accurate wave-function methods to determine the influence of terrestrially available magnetic fields on water. The work of this thesis presents important contributions to theoretical chemistry in the pres- ence of magnetic fields.

• Tellgren, Erik; Lange, Kai Kaarvann; Sagvolden, Espen; Kvaal, Simen; Austad, Jon; Reimann, Sarah; Borgoo, Alex; Fliegl, Heike; Sen, Sangita & Helgaker, Trygve (2018). Quantum chemistry for strong magnetic fields.
• Austad, Jon (2014). Møller-Plesset Perturbation Theory With and without laplace transform ansatz in strong magnetic fields using London type orbitals.
• Austad, Jon Henriksen (2013). Møller-Plesset theory to second order for the study of molecuar systems in finite magnetic fields. Vis sammendrag

  London orbitals allows for non-perturbative treatment of magnetic fields. This can be used to explore how molecules behave in very strong finite magnetic fields, and also be used to probe complicated magnetic properties like hypermagnetizability without resorting to response theory. Classical MP2 and an atomic orbital based variant of MP2 with a Laplace transform ansatz were introduced to the London program, and successfully used to perform different quantum chemical calculations entailing magnetic fields of finite size.

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