In this paper we present the implementation and benchmarking of a Time Dependent Density Functional Theory approach in conjunction with Double Hybrid (DH) functionals. We focused on the analysis of their performance for through space charge‐transfer (CT) excitations which are well known to be very problematic for commonly used functionals, such as global hybrids.Two different families of functionals were compared, each of them containing pure, hybrid and double‐hybrid functionals.The results obtained show that, beside the robustness of the implementation, these functionals provide results with an accuracy comparable to that of adjusted range‐separated functionals, with the relevant difference that for DHs no parameter is tuned on specific compounds thus making them more appealing for a general use. Furthermore, the algorithm described and implemented is characterized by the same computational cost scaling as that of the ground state algorithm employed for MP2 and double hybrids.
In this work we develop and apply a tool allowing for a condensed analysis of the nature and energetics of the electronic excited states computed using Time Dependent Density Functional Theory (TD-DFT) inspired by the transition contribution map (TCM) analysis of Hakkinen and collaborators. This new analysis will be referred to as Global Transition Contribution Grid (G_TCG) and will be applied to compare the behavior of two families of exchange correlation functionals for the description of the excited states of a series of five polycyclic aromatic hydrocarbons (PAH) molecules. These latter are indeed known to be problematically described at the excited state by local and semi-local exchange correlation functionals. Although further improvement is possible, our results show that G_TCG can be used to qualitatively spot difference in the behavior of the different functionals not only in energetics but also in the nature of the computed transitions in a condensed and qualitative way.More generally, the global grid based analysis could help in the analysis of the excited states of systems possessing a complex electronic structure and a dense molecular orbitals manifold close to the frontier orbitals, such as nanoparticles or large -conjugated systems, for which several hole-electron pairs are expected to contribute to single electronic transitions.
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