Coupled-Cluster in Density Functional Theory Embedding Applied to Static Polarizabilities in Aqueous Environments

We present a study of static polarizabilities of organic molecules in aqueous environments using projection-based coupled-cluster in density functional theory quantum embedding. We propose two methods for the computation of supermolecular polarizabilities: an iterative embedding approach and a finite-field approach. The performance of these methods is tested against regular coupled-cluster singles and doubles (CCSD) theory. The static polarizability tensor of the investigated organic molecules varies only slightly with the inclusion of water molecules. The iterative CCSD-in-DFT approach produces isotropic polarizabilities of CCSD quality with mean relative errors smaller than 1.0% at a reduced computational cost, while the anisotropic polarizabilities are not as well described. The choice of the exchange correlation functional for the treatment of the environment has little impact on the quality of the iterative embedding results. On the other hand, the results of the finite-field approach heavily depend on the density functional. When the best performing functionals are used, the finite-field approach yields isotropic and anisotropic polarizabilities in very good agreement with CCSD.