Prediction of charge-transfer excitations in coumarin-based dyes using a range-separated functional tuned from first principles

摘要

We study the description of charge-transfer excitations in a series of coumarin-based donor-bridge-acceptor dyes.We show that excellent predictive power for the excitation energies and oscillator strengths in these systems is obtained by using a range-separated hybrid functional within the generalized Kohn–Sham approach to time-dependent density functional theory. Key to this success is a step for tuning the range separation parameter from first principles.We explore different methods for this tuning step, which are variants of a recently suggested approach for charge-transfer excitations T. Stein et al., J. Am. Chem. Soc. 131, 2818 (2009).We assess the quality of prediction by comparing to excitation energies previously published for the same systems using the approximate coupled-cluster singles and doubles (CC2) method.