Theoretical Investigations of Molecular Electronic Structure in a Magnetic Field

Abstract

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.