Is the Tamm-Dancoff Approximation Reliable for the Calculation of Absorption and Fluorescence Band Shapes?

摘要: The reliability of the Tamm-Dancoff approximation (TDA) for predicting vibrationally resolved absorption and emission spectra several prototypical conjugated molecules has been addressed by performing a series extensive theoretical calculations. To this end, we have systematically compared TDA results with full Time-Dependent Density Functional Theory (TDDFT), Random Phase Approximation (RPA), as well Configuration Interaction Singles (CIS) methods that are routinely employed prediction optical large molecules. Comparisons made experimental both band shapes 0-0 energies. They revealed is generally able to reproduce along positions peaks. With respect TDDFT, leads an underestimation relative intensities most cases but does not alter any other feature spectra. For case energies, it better agreement between theory experiment TDDFT majority studied, at least when combined popular B3LYP functional.