On combining the conductor-like screening model and optimally tuned range-separated hybrid density functionals.

Abstract

Range-separated hybrid functionals whose range-separation parameter γ has been nonempirically tuned to a particular molecule have been shown to yield frontier orbital energies and other properties in very good agreement with experiments. However, many cases, such as organic optoelectronic devices, require the description of molecules embedded in an environment. This can be done by combining the γ-tuning procedure with polarizable continuum models in general and the very versatile conductor-like screening model in particular. There are at least two different ways of performing this combination. The partially vertical γ-tuning employs equilibrium solvation throughout. The strictly vertical γ-tuning, on the other hand, employs nonequilibrium solvation to obtain ionization energies. In this article, we compare ground-state and excited-state properties of several different molecules relevant to organic optoelectronics that were obtained using both of the two different tuning procedures. While there are significant differences in the ground-state properties, we see virtually no difference in the excited-state properties. Given these results, we conclude that both tuning procedures have to be used in conjunction for the correct description of both ground-state and excited-state properties.