Density functional study of the electronic structure and properties of lithium intercalated graphite

Ab initio electronic-structure calculations are performed using density functional theory (DFT) with polarized basis set (LanL2DZ and 6-311G(++)) within the spin polarized generalized gradient approximation for lithium intercalated graphite. Initially different benzene-Li+ model clusters are optimized on the basis of their total energy at room temperature. These model clusters are used to calculate the optimized structure of lithium intercalated graphite clusters. The resultant optimized structures are used to calculate dipole moment, ionization potential (IP), electron affinity (EA), binding energy (BE) and vibrational spectra (IR and Raman). For an idea of the band gap of the clusters in the ground state, the HOMO-LUMO gap (Delta E-g) has been calculated. To compare the electron transfer ability of different clusters, chemical potential (mu), hardness (eta) and their ratio (|mu/eta|) for different clusters have also been determined.