Accurate evaluation of valence and low-lying Rydberg states with standard time-dependent density functional theory.
Using a standard exchange-correlation functional, namely, PBE0, the basis set dependence of time-dependent density functional theory (TD-DFT) calculations has been explored using 33 different bases and five organic molecules as test cases. The results obtained show that this functional can provide accurate (i.e., at convergence) results for both valence and low-lying Rydberg excitations if at least one diffuse function for the heavy atoms is included in the basis set. Furthermore, these results are in fairly good agreement with the experimental data and with those delivered by other functionals specifically designed to yield correct asymptotic/long-range behavior. More generally, the PBE0 calculations show that a greater accuracy can be obtained for both Rydberg and valence excitations if they occur at energies below the epsilonHOMO + 1 eV threshold. This latter value is proposed as a thumb rule to verify the accuracy of TD-DFT/PBE0 applications.
Ciofini
Ilaria
I
Laboratoire d'Electrochimie et Chimie Analytique, Ecole Nationale Supérieure de Chimie de Paris, UMR CNRS 7575, 11 rue Pierre et Marie Curie, F-75231 Paris Cedex 05, France.
Adamo
Carlo
C