The computation of electronic absorption or circular dichroism (CD) spectra of molecules with a system size of 1000 atoms or more is challenging. However, CD spectroscopy is an important tool for structure elucidation of biomolecular systems or characterization of transition metal complexes. We previously developed the simplified variants of Tamm-Dancoff approximated (sTDA)[1] and time-dependent (sTD)[2] density functional theory which are based on a regular ground state Kohn-Sham determinant (obtained with hybrid or range-separated hybrid functionals[3]). This approach enables the computation of electronic spectra with TD-DFT ac- curacy for molecules up to a few hundred atoms. The computation of the ground state is the computational bottleneck. Our recently developed tight-binding method using an extended AO basis set (xTB)([4]) solves this problem and enables the ultra-fast computation of electronic spectra by sTDA-xTB. Computed spectra for biomolecular sytems, e.g, for entire exemplary proteins and DNA fragments, as well as large transition metal complexes are presented. [1] S. Grimme, J. Chem. Phys. 138, 244104 (2013). [2] C. Bannwarth, S. Grimme, Comput. Theor. Chem. 45, 10401041, (2014). [3] T. Risthaus, A. Hansen, S. Grimme, Phys. Chem. Chem. Phys. 16, 14408 (2014). [4] S. Grimme, C. Bannwarth J. Chem. Phys. 145, 054103 (2016).

Electronic excitation spectra calculation of large systems with a tight-binding based simplified Tamm-Dancoff approximation (sTDA-xTB)

255th National Meeting (2018)

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