An implementation of a complex solver for the solution of the response equations required to compute the complex response functions of damped response theory is presented for the resolution-of-identity (RI) coupled-cluster singles and approximate doubles CC2 method. The implementation uses a partitioned formulation that avoids the storage of double excitation amplitudes to make it applicable to large molecules. The solver is the keystone element for the development of the damped coupled-cluster response formalism for linear and nonlinear effects in resonant frequency regions at the RI-CC2 level of theory. Illustrative results are reported for the one-photon absorption cross section of C60, the electronic circular dichroism of n-helicenes (n = 5, 6, 7), and the C6 dispersion coefficients of a set of selected organic molecules and fullerenes.
@article{arxiv.2101.03756,
title = {Damped (linear) response theory within the resolution-of-identity coupled cluster singles and approximate doubles (RI-CC2) method},
author = {Daniil A. Fedotov and Sonia Coriani and Christof Hättig},
journal= {arXiv preprint arXiv:2101.03756},
year = {2022}
}