Theoretical Investigations of Transition Metal Carbides Jie Song Department of Chemistry and Biochemistry University of Michigan-Flint, MI 48502 Compared with the more and more interests in nanomaterials, our understanding on their chemical bonding characteristics are very limited and limited number of studies lead to the contradicted conclusions. As a result, small model compounds, like transition metal carbides, have received considerable attentions from experimentalists and theoreticians. In this study, we systematically studied the effect of scalar relativistic effect, the dynamic electron correlation, the size of the active space, and the size of the basis set in describing the electronic structures of NiC2 . Currently, the similar studies have been extended to studies of ground states and low-lying excited states of two analogs, CrC2 and CuC2. Comparisons of three molecules may supply the chemical insight into the bonding.