Photoabsorption and Photo-induced absorption in Conjugated Polymers

We present the results of calculated photoabsorption and photo-induced absorption in conducting polymers with electron-electron correlation included. Electron correlation effects is essential in understanding conducting polymers quantitatively. We adopt the SSH Hamiltonian supplemented by an on-site Hubbard term as our model Hamiltonian and use the density matrix renormalization group mehtod to determine the low-lying excited states. We'll present the results of polaron absorption; photo-induced absorption of triplet state and that of the B_1u state.