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

Abstract

We investigate the performance of a set of recently introduced range-separated double-hybrid functionals, namely ωB2-PLYP, ωB2GP-PLYP, RSX-0DH, and RSX-QIDH models for hard-to-calculate excitation energies. We compare with the parent (B2-PLYP, B2GP-PLYP, PBE0-DH, and PBE-QIDH) and other (DSD-PBEP86) doublehybrid models as well as with some of the most widely employed hybrid functionals (B3LYP, PBE0, M06-2X, and ωB97X). For this purpose, we select a number of medium-sized intra-and inter-molecular charge-transfer excitations, which are known to be challenging to calculate using time-dependent density-functional theory (TD-DFT) and for which accurate reference values are available. We assess whether the high accuracy shown by the newest double-hybrid models is also confirmed for those cases too. We find that asymptotically corrected double-hybrid models yield a superior performance, especially for the inter-molecular charge-transfer excitation energies, as compared to standard double-hybrid models. Overall, the PBE-QIDH and its corresponding range-separated RSX-QIDH functional are recommended for general-purpose TD-DFT applications, depending on whether long-range effects are expected to play a significant role.

Violation of Hund’s rule in molecules: Predicting the excited-state energy inversion by TD-DFT with double-hybrid methods

“…That contribution is known to be an individual quantity for each functional, molecule, and excited state, which in fact determines the final quality of an excitation energy calculated by a double-hybrid density functional. [97][98][99] Figure 5 presents the magnitude of that term for the standard B2-PLYP, PBE-QIDH, and PBE0-2 expressions, which differ in their a c weight (a c = 0.27, a c = 1/3, and a c = 1/2, respectively) and for both excitation energies (S 1 ← S 0 and T 1 ← S 0 ) for the whole set of systems. The first observation is how the magnitude of the correction for S 1 ← S 0 excitation energies increase with a c , as expected, ranging from -0.24 to -0.71 eV for B2-PLYP, from -0.26 to -0.76 eV for PBE-QIDH, and from -0.38 to -1.09 eV for PBE0-2.…”

Time-Dependent Long-Range-Corrected Double-Hybrid Density Functionals with Spin-Component and Spin-Opposite Scaling: A Comprehensive Analysis of Singlet–Singlet and Singlet–Triplet Excitation Energies

“…[58][59][60][61][62][63][64] Prior to mid-2020, most of the BLYPbased global DHDFAs studies had been carried out using the full TD-DHDFA scheme, whereas most of the studies using PBE-based global DHDFAs had used the TDA-DHDFA scheme, instead. 37,38,[65][66][67][68][69][70][71][72][73][74][75] Moreover, all previous benchmark studies and applications had been limited to singlet-singlet excitations, except for the original work by Grimme and Neese from 2007, 18 leaving out other spin multiplicities of crucial relevance, such as triplet excitations, most likely due to the lack of a code that could handle those transitions. For this reason, we assessed for the first time singlet-singlet and singlet-triplet excitations with global-and LC-DHDFAs based on both BLYP and PBE expressions for the underlying exchange-correlation functional and compared them with hybrid functionals.…”

Spin-Scaled Range-Separated Double-Hybrid Density Functional Theory for Excited States

“…Next, we study CT excitations, which present a well-known problem even in this class of methods. ,, The numerical results for the CT benchmark set of Szalay et al are presented in Figure . Inspecting the errors, the advantages of the range separation become clear since only these functionals can provide acceptable results compared to the wave-function-based methods.…”