Low lying optically excited states of conjugated polymers with DMRG

We present the results of a density matrix renormalization group (DMRG) study which reveals the nonlinear optical properties of long chain systems within the extended Hubbard model. We use a combination of the infinite and finite system DMRG methods to calculate the dipole couplings between eigenstates, and are thus able to target the “essential” states which dominate the nonlinear optical response of these materials. Specifically we investigate the 1Bu optical exciton, the mAg (a higher energy even-parity exciton) and the nBu, which has previously been identified as the threshold of the electron-hole continuum.