UNDERSTANDING AND DESIGNING COMPLEX POTENTIAL ENERGY LANDSCAPES ACROSS THE NANOSCALE

211 pages ; In this thesis, I will discuss four projects I participated during my Ph.D. study, with an emphasis on understanding and designing complex energy landscape between molecules and materials across nanoscale. These research projects are organized into four chapters: Chapter 1: Designer Potential Energy Surfaces via Programmable Magnetic Interactions; Chapter 2: Influence of Pore Size on the van der Waals Interaction in Two-Dimensional Molecules and Materials; Chapter 3: Non-Additivity and Finite-Size Effects in the Polarizabilities and Dispersion Coefficients of the Fullerenes; Chapter 4: Competitive Adsorption as a Route to Area-Selective Deposition. In Chapter 1, we explore how programmable magnetostatic interactions can be used in the rational design of Potential Energy Surfaces (PES) with targeted features. We first explore the PES design space that is accessible with small patterned magnetic arrays via forward and exhaustive enumeration, and characterize the resulting PES by the number, locations, and depths of the PES critical points. This is followed by a detailed investigation into the inverse problem—identification of magnetic patterns that correspond to PES with predefined features—using simulated annealing Monte Carlo (SA-MC) methods. In doing so, we demonstrate a robust theoretical and conceptual paradigm that enables forward and inverse PES engineering with precise control over the critical points and other salient surface features, thereby paving the way towards directed self-assembly using programmable magnetic interactions. As the magnetic interactions are scale-invariant, this approach can essentially scale down to the nanoscale. In Chapter 2, we investigate the influence of void space in porous twodimensional (2D) molecules and materials systems to the van der Waals (vdW) scaling landscape [1]. Analytical and numerical models presented herein demonstrate that the mere presence of a pore leads to markedly different vdW scaling across non-asymptotic distances, with certain relative pore ...