The study of uranium carbides has received renewed attention in recent years due to the potential use of these compounds as fuels in new generations of nuclear reactors. The isomers of the UC6 cluster were determined by DFT and ab initio methods. The structures obtained using SCRECP for U were generally consistent with those obtained using an all-electron basis set (ZORA-SARC). The CCSD(T) calculations indicated that two isomers had similar energies and may coexist in laser evaporation experiments. The nature of the U-C bonds in the different isomers was examined via a topological analysis 'of the electron density, and the results indicated that the U-C bonds are predominantly closed-shell (ionic) interactions with a certain degree of covalent character spectra of the isomers were theoretically simulated to provide information that can be used to identify the isomers of UC6 in future experiments.