Time-domain quantum dynamics: Optical properties from time-dependent electronic-structure theory

Abstract

Within the field of nonlinear optics, nonlinear optical properties are defined as frequency-dependent responses. This definition emerged in the frequency domain, as lasers used in these early experiments emitted monochromatic continuous waves. This led to the development of time-dependent electronic-structure theory predominantly in the frequency domain, using perturbation-theory based response theory. However, in recent years, advances in computing power and the advent of ultrashort laser pulses have sparked interest in the time-domain for both electronic-structure theory and nonlinear optics. Time-domain electronic-structure theory provides a time-resolved description of light-matter interaction, closely mimicking experiment. Additionally, they offer the advantage of highly nonlinear responses being straightforward to implement. This thesis contributes to the field of time-domain time-dependent electronic-structure theory for the description of nonlinear optical properties by: Investigating the potential of dynamic (time-dependent) orbitals for improving the description of nonlinear optical properties, extending a hierarchy of time-domain time-dependent coupled-cluster methods to accommodate strong magnetic fields, and by developing an efficient approach for extracting higher-order response properties.