Time-dependent density functional theory: A tool to explore excited states

Abstract

The accurate description of electronically excited states remains a challenge for theoretical chemistry. Among the vast body of quantum mechanical methods available to perform this task, time-dependent density functional theory (TD-DFT) currently remains the most widely applied method, a success that one can explain not only by its very interesting accuracy/effort ratio but also by the ease to perform TD-DFT calculations for a large number of compounds and properties (absorption and emission spectra, band shapes, dipole moments, electron and proton transfers, etc.) in various environments. In the present chapter, we present TD-DFT as a tool for modeling such excited-state properties, with a focus on several practical aspects (choosing an exchange-correlation functional and an atomic basis set, analyzing the nature of the electronic transitions, comparing results with experiments, including environmental effects, etc.) that are useful to get a quick start. In that framework we rely on a series of examples of increasing complexity considering both organic and inorganic compounds as well as biomolecules.