Damped (linear) response theory within the resolution-of-identity coupled cluster singles and approximate doubles (RI-CC2) method

An implementation of a complex solver for the solution response equations required to compute functions damped theory is presented resolution-of-identity (RI) coupled-cluster singles and approximate doubles CC2 method. The uses partitioned formulation that avoids storage double excitation amplitudes make it applicable large molecules. keystone element development formalism linear nonlinear effects in resonant frequency regions at RI-CC2 level theory. Illustrative results are reported one-photon absorption cross section C60, electronic circular dichroism $n$-helicenes ($n$ = 5, 6, 7), $C_6$ dispersion coefficients set selected organic molecules fullerenes.