Extension of the element parameter set for ultra-fast excitation spectra calculation (sTDA-xTB)

Abstract

ABSTRACTThe extension of the parameter set for an ultra-fast electronic excitation spectra calculation is presented. The semiempirical theory based on a tight-binding approach, called extended tight-binding (xTB) in combination with the simplified Tamm-Dancoff approximation (sTDA) shows remarkable accuracy at very low computational cost for the calculation of vertical excitation energies of molecules. It enables the possibility for computing even large systems up to thousands of atoms or sampling along molecular dynamic (MD) trajectories. The original publication of the sTDA-xTB method included parameters for the most important elements (H-Zn,Br,I). In this work, element parameters for 4d and 5d metals, and the missing ones in 4p, 5p and 6p element blocks are presented and analysed for their quality. Comparisons to theory and experiment show that sTDA-xTB provides similar good results as for the elements in the original publication with an average deviation of excitation energies of 0.3–0.5 eV.