For simulating the excitation energies and absorption spectra of chromophores in complex environments, time-dependent density functional theory (TDDFT) is often the method of choice.   However, accurately modeling absorption lineshapes for molecules in solution requires not only accurate excitation energies, but also capturing both inhomogeneous broadening and vibronic broadening. In this talk I will compare different ways of modeling inhomogeneous broadening within TDDFT, including using the solvent reorganization energy, using an ensemble sampling of TDDFT vertical excitation energies, and allowing full coupling between the chromophore and solvent by computing spectra via the energy gap autocorrelation function. I will also present our new method of combining ensemble sampling at a given temperature with a zero-temperature vibronic spectrum and compare this to more rigorous approaches for modeling absorption lineshapes.<br/>

Using TDDFT for improved absorption lineshapes for molecules in solution: Combining ensemble sampling, vibronic effects, and energy gap autocorrelation functions

256th National Meeting (2018)

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