Theoretical Investigation of the Vibrational and Electronic Properties of Titanium Carbide Nanocrystals

Stable titanium carbide nanoclusters with \verb+~+1:1 stoichiometry were first discovered in molecular-beam experiments in the early 1990's. These clusters are all indexed to perfect or nearly perfect $N_1 \times N_2 \times N_3$ fragments of bulk TiC in the rocksalt structure and are thus termed ``nanocrystals''. The most abundant member of this family is the $3\times 3 \times 3$ nanocrystal Ti$_{14}$C$_{13}$, indicating special stability for this species. Using Density Functional Theory, we have carried out a detailed theoretical analysis of the structural, electronic, and vibrational states of Ti$_{14}$C$_{13}$ and its $3 \times 3 \times 3$ sibling, Ti$_{13}$C$_{14}$, which is not observed in the experiments. In this talk, we will present our theoretical results and show how our analysis sheds light on several previously unresolved experimental findings.