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Abstract: Density and time-dependent density functional theory have been used to simulate the vibronic structure of the emission and absorption spectra of a typical trimethine cyanine dye. This approach combines the BH and HLYP exchange-correlation functional with the Doktorov scheme to evaluate the Franck–Condon factors. The absorption and emission spectra present a dominant band and a shoulder, which nicely reproduce the experimental data. The theoretical calculations demonstrate that the simplicity of the shape results from rather small geometry relaxations in the first excited state, though many vibrational normal modes contribute to it. [Copyright &y& Elsevier]

We present a combined density functional/time-dependent density functional study of the electronic structure and optical absorption spectrum of the charge-transfer sensitizer cis-[Ru(4,4′-COOH-2,2′-bpy)2(NCS)2] in water solution. To simulate the effect of different pH values, calculations have been performed for both the title complex and the corresponding tetra-deprotonated species, cis-[Ru(4,4′-COO-2,2′-bpy)2(NCS)2]4−. The experimentally observed blue-shift of the spectrum at high pH is well reproduced by our theoretical model and appears to be related to destabilization of the bipyridines π* LUMOs as a result of the increased electron density on the deprotonated carboxylic groups. [Copyright &y& Elsevier]