On the Nature of Self-Consistency in Density Functional Theory

A thesis providing a pedagogical introduction to the problem of achieving self-consistency in density functional theory. Contained is an introduction to the framework of Kohn-Sham density functional theory, leading then to the considerations required to solve the equations of Kohn-Sham density functional theory. Specifically, a focus is placed on where current self-consistent field methodology is inefficient and/or fails to converge to a solution. As such, this review spans sub-disciplines such as numerical analysis of linear and non-linear systems, linear response theory, and general electronic structure theory. Toward the end of the thesis, certain contemporary methods for achieving self-consistency from literature are outlined, and a novel, computationally efficient preconditioning strategy is proposed. This work is implemented in the CASTEP software.