| This dissertation focuses on two theoretical research topics: Multiscale Simulations of Single-Walled Carbon Nanotube Atomic Force Microscopy (AFM, chapters 1 through 3) and Density Functional Theory Characterization of Functionalized and non-functionalized Silicon Surfaces (chapters 4 through 8,). The first topic presents the development of an AFM simulation methodology, based on first principles, which incorporates the atomistic details of probe, sample, and impurities in the construction of the images. It also includes studies of the influence of common artifacts (such as elastic deformations and imaging multistability) and probe structure (tilt angle and number of walls in the carbon nanotube probe) on image quality. The second topic concerns the structure and energetics of reconstructed and unreconstructed silicon (111) surfaces (either functionalized with groups such as methoxy and methyl or without functionalization) and non-functionalized copper-silicon surfaces and crystals. These studies lead to novel findings such as the formation of a full stacking fault on the methylated Si(111) surface in the presence of large etch pits and the quantification of the surface energy path of the Si(111) 1x1 → DAS 7x7 reconstruction. Most of this work was done in collaboration with experimental groups and is in agreement with the most current experimental results. |
