In the field of molecular dynamics (MD), the time evolution of a set of interacting
atoms is determined by integrating their equations of motion using Newton’s Second
Law. By using efficient potentials that capture the essential physics of a material,
the properties of systems containing tens of thousands of atoms can be accurately
modelled. This thesis describes three substantial developments in the science and
simulation of ionic materials. In the opening chapters, we provide an introduction
to the field of atomistic simulation, covering the theory and methods used in
both classical molecular dynamics and density-functional theory (DFT). The use of
DFT calculations in the parametrisation of force fields for molecular dynamics is
described, and we discuss how the software used for MD and potential parametrisation
has been radically overhauled and made more efficient and user friendly during
the course of this work.
We then study aluminium oxide, and develop a new potential which is faster and
simpler than the current state of the art alumina potentials. The new potential is
tested and found to accurately describe a range of physical properties. The potential
is then applied to the study of intrinsic defects in alumina.
Finally, we attempt to improve our description of heterogeneous ionic materials
by developing and implementing a coupled charge-equilibration and polarisable ion
model applicable to non-molecular systems. A review of the existing literature on
the subject is made, before we describe the mathematical and physical reasoning
behind our new implementation. Our method is found to be numerically accurate,
and is subsequently applied to the study of defects and surfaces in magnesium oxide.