LINEAR AND NONLINEAR-OPTICAL RESPONSE OF POLYENES - A DENSITY-MATRIX RENORMALIZATION-GROUP STUDY

Using a symmetry adapted density matrix renormalization group (DMRG) f ormulation, we have calculated various optical spectra, including line ar absorption, electroabsorption, third-harmonic generation, and two-p hoton absorption, for a series of linear polyene molecules (up to 40 c arbon sites) modeled by an extended Hubbard-Peierls Hamiltonian within the intermediate correlation regime. The theoretical two-photon absor ption spectrum for trans-octatetraene is in good agreement with experi ment. By comparing the experimental linear absorption spectra and theo retical higher A(g) state energies, it is suggested that the so-called cis-band actually corresponds to the threshold of the mA(g) band. (C) 1998 American Institute of Physics.