Time-independent coupled cluster theory of the polarization propagator. Implementation and application of the singles and doubles model to dynamic polarizabilities and van der Waals constants

Recently proposed time-independent coupled cluster theory of the polarization propagator [R. Moszynski, P. S. Zuchowski, and B. Jeziorski, Collect. Czech. Chem. Commun. 70, 1109, 2005] has been implemented at the single and double excitations (CCSD) level. The performance of the new approach was investigated by carrying out calculations of static and dynamic electric dipole polarizabilities for various molecules and by making a comparison with values obtained from other ab initio methods, including the full configuration interaction (FCI) technique. Our results show that the polarizabilities computed with the new approach are in a good agreement with the time-dependent CCSD and (when available) FCI values. The isotropic C-6 dispersion coefficients for several benchmark van der Waals complexes, e. g. dimers of helium, argon, water, and benzene, are also reported. They compare very well with existing experimental and best theoretical data. The new propagator, implemented already in the MOLPRO package, is computationally somewhat less demanding than the propagator of the time-dependent coupled cluster theory, and can be considered as an alternative to the latter in applications to large molecules and in studies of their interactions.