A relativistic treatment of atoms and molecules : from relativity to electroweak interaction : a thesis submitted in partial fulfillment of the requirements of the degree of Doctor of Philosophy in Theoretical Physics at Massey University, Auckland, New Zealand
Relativistic quantum chemistry is the relativistic formulation of quantum mechanics applied to many-electron systems, that is to atoms, molecules and solids. It combines the principles of special relativity, which are obeyed by any fundamental physical theory, with the basic rules of quantum mechanics. By construction, it represents the most fundamental theory of all molecular sciences, which describes matter by the action, interaction and motion of the elementary particles. This science is of vital importance to physicists, chemists, material scientists, and biologists with a molecular view of the world A full relativistic treatment of atoms and molecules which includes the quantization of the electromagnetic field is currently one of the most challenging tasks in electronic structure theory. Therefore, relativistic effects in atoms and molecules were studied computationally. A combination of wave function and density functional based methods within a correct relativistic framework proved necessary to achieve accurate results of various atomic and molecular properties. The first part of this thesis deals with investigations in atomic systems including quantum electrodynamic effects in the ionization potentials of a large number of elements K-shell and L-shell ionizations potentials for 268Mt were calculated and static dipole polarizabilities of the neutral group 14 elements were investigated. The second part concentrates on molecular systems including superheavy element monohydrides up to 120H+). In particular, the chemical bonding of the superheavy elements 119 and 120 are investigated for the first time. Electric field gradients of a number of gold and copper compounds were also calculated and the nuclear quadrupole moment of gold and copper determined in good agreement with experiment. Finally, the parity violation energy difference in the chiral molecule bromochlorofluoromethane (CHFCIBr) was investigated by relativistic coupled-cluster theory to provide benchmark results for all future investigations in this field.