Structure and Surface Properties of Nanodiamonds: A First-Principles Multiscale Approach

The goal of this work is to gain fundamental understanding of the surface structure of functionalized detonation nanodiamonds (NDs) using quantum mechanics (QM) based multiscale modeling and simulation. The study entails a multiscale approach to bridge the length scale between the real sizes of ND being fabricated (∼4 nm) and the size allowed by employing first-principles based modeling (< 1 nm). At first, the structure of NDs of technologically relevant size (∼4 nm) was optimized using classical mechanics based molecular mechanics simulations. QM based density functional theory (DFT) was then employed to simulate the structure and analyze the properties of relevant parts of the optimized cluster. This work is extended to NDs functionalized with carboxylic acid (-COOH) and carbonyl oxygen (=O), which help to guide further experiments on functionalization of NDs and their use as carriers of drug molecules to the desired site.