Double hybrids and time‐dependent density functional theory: An implementation and benchmark on charge transfer excited states

Abstract

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.

CPL Spectra of Camphor Derivatives in Solution by an Integrated QM/MD Approach

“…In order to increase the accuracy of the results, all the transition energies were shifted with reference to the values computed in the gas-phase at the Cis(d) B2PLYPD3/jun-cc-pVTZ level, which is significantly more reliable than TD-DFT with hybrid functionals (Grimme and Neese, 2007;Jacquemin et al, 2009;Laurent and Jacquemin, 2013;Ottochian et al, 2020). The first step was the simulation of the absorption spectra.…”

“…Free energies were determined by adding to electronic energies zero-point energy, thermal, and PCM solvation contributions evaluated in the framework of the rigid rotor/harmonic oscillator approximation (Bloino et al, 2012 ; Cappelli et al, 2012 ; Mennucci, 2012 ). Transition energies have been corrected by the differences between TDDFT/CAMB3LYP/jul-cc-pVDZ and Cis(d) B2PLYPD3/jun-cc-pVTZ (Grimme and Neese, 2007 ; Jacquemin et al, 2009 ; Ottochian et al, 2020 ) (B2) results for isolated camphor. The LAM associated with the double-well potential has been characterized in the framework of the ICPH-model (Baiardi et al, 2017 ), using 251 DVR basis functions and a step size of 4°.…”

Assessing challenging intra‐ and inter‐molecular charge‐transfer excitations energies with double‐hybrid density functionals

“…We will also consider a set of radical (open-shell) small molecular systems, taken from the last work of Loos et al, 52 emitting diodes to circumvent the difficulty in harvesting triplet excitons, typical of closed-shell emitters. 53,54 Since DH functionals are being progressively and successfully implemented in widely used codes, 55,56 we hope this assessment will further stimulate both the development and the use of such methods for excited-state applications, as their accuracy for all kind of excitation energies is confirmed.…”

A New Benchmark Set for Excitation Energy of Charge Transfer States: Systematic Investigation of Coupled Cluster Type Methods

“…The same conclusion holds for double hybrids in the context of CT states. 10 Recent studies also found the restricted open-shell Kohn–Sham approach a promising way of obtaining CT states by DFT methods. 11 , 12 For more recent developments in the treatment of charge transfer states within TDDFT, the reader is referred to two excellent reviews on the subject.…”