Tight-binding approach to time-dependent density-functional response theory - art. no. 085108

In this paper we propose an extension of the self-consistent charge-density -functional tight-binding (SCC-DFTB) method [M. Elstner et al., Phys. Rev. B 58, 7260 (1998)], which allows the calculation of the optical properties of finite systems within time-dependent density-functional response theory (TD-DFRT). For a test set of small organic molecules low-lying singlet exci tation energies are computed in good agreement with first-principles and ex perimental results. The overall computational cost of this parameter-free m ethod is very low and thus it allows us to examine large systems: we report successful applications to C-60 and the polyacene series.