Energetics and bonding in small lithiated carbon clusters

Small carbon clusters metallized with Li were studied within a hybrid density functional approach with generalized gradient correction. Structures of the ground state and several excited states associated with different isomers and multiplicities were systematically calculated for CxLiy with x = 1-3 and y = 1-5. The most stable isomers are either linear or planar in the ground state. Three-dimensional structures are only identified for CLi4, CLi5, and C3Li4. There is important charge transfer in these compounds, showing that ionic bonding is favored as the cluster grows in size. Ionization potentials, electron affinities, and the vibrational analysis of all studied states is provided for all clusters. Structural transitions are predicted for C2Li2 at 1400 K and C2Li4 at 420 K.