Performance of DFT Methods in the Calculation of Optical Spectra of Chromophores

We present electronic structure calculations on the ultraviolet/visible (UV-Vis) spectra of highly active pushpull chromophores. In particular, we have implemented and applied the recently developed long-range corrected Baer-Neuhauser-Livshits (BNL) exchange-correlation functional. We have implemented this functional in the NWChem program package. The UV-Vis spectra obtained with the BNL functional are found to be superior compared with other density functional theory (DFT) functionals. The method captures the charge-transfer states particularly well while the pi-pi* excitations are less accurate. Consideration of the chromophore conformations also improves the strength of the pi-pi* excitations.