ABSTRACT
Secondly, there is the class of bottom-up atomistic-molecular methodologies (from the so-called microscopic perspective) that include ab initio quantum, molecular dynamic, tight-binding, and appropriate Monte Carlo modeling methods among others. No emphasis is placed on these methods in this chapter although such approaches have reached high levels of sophistication and versatility and, due to enhanced computing capability, have achieved success in modeling nanomaterials and other materials as large and complex as proteins-from the bottom-up [1,2]. With regard to outcomes of optical studies from such a microscopic perspective, tight-binding molecular dynamic (TBMD) simulations have experienced some utility. For example, optical/electronic properties (e.g., the optical gap) of amorphous-carbon/tetrahedral-carbon mixtures have been determined by application of TBMD methods. In such work, based on a quantum mechanical description of electronic interactions and a “reliable environment-dependent Hamiltonian,” macroscopic dielectric functions were generated that correlated well with experimentally determined measurements by ellipsometry [3].
