Local approach to coupled cluster evaluation of polarizabilities for long conjugated molecules

Electron correlation effect in conjugated polymer is a long-standing problem, especially for the nonlinear optical properties. We have implemented a spin-adapted Coupled Cluster with singles and doubles excitation with local molecular orbital approach. As a first application, we evaluate the static polarizability of conjugated polyene chains with finite field approach. It is found that the local molecular orbital approach can tremendously reduce the computational costs at sufficiently high accuracy. It is also found that the electron correlation can largely reduce the molecular polarizability with respect to the Hartree-Fock mean field results.