PhD thesis Robert Rüger: Fast Excited State Calculations
Congratulations to Dr. Robert Rüger! On 14 February Robert successfully defended his PhD thesis entitled Approximations in Density Functional Based Excited State Calculations, describing the development, benchmarking and applications of fast methods for UV/VIS methods.
Robert first implemented time-dependent density functional tight-binding (TDDFTB), including gradients to enable vibrationally resolved emission and absorption spectra. For large systems intensity selection can reduce the compute time enormously without compromising the accuracy.
Later he applied the approximations involved in the linear response part of TDDFTB to DFT. The bottleneck in this so-called TD-DFT+TB approach is the calculation of the Kohn-Sham orbitals at the DFT level, again enabling optical spectra of much larger systems than with traditional LR-TDDFT. This approach is related to the simplified TDDFT and TDA approaches of Grimme and especially improves the description of higher-lying excited states because it is not limited to a minimal basis (unlike DFTB).