Double-hybrid density functionals: merging wavefunction and density approaches to get the best of both worlds

Abstract

We review in this Perspective why and how double-hybrid density functionals have become new leading actors in the field of computational chemistry, thanks to the combination of an unprecedented accuracy together with large robustness and reliability. Similarly to their predecessors, the widely employed hybrid density functionals, they are rooted on the Adiabatic Connection Method from which they emerge in a natural way. We present recent achievements concerning applications to chemical systems of the most interest, and current extensions to deal with challenging issues such as non-covalent interactions and excitation energies. These promising methods, despite a slightly higher computational cost than other typical density-based models, are called to play a key role in the near future and can thus pave the way towards new discoveries or advances.2

Theoretical Rationalization of the Singlet–Triplet Gap in OLEDs Materials: Impact of Charge-Transfer Character

“…For the case of PhCz, for which it seems clearly established the presence of an absorption maximum peaking at around 3.67 eV 79 almost independent of solvent effects, we have compared the output of some Double-Hybrid (DH) expressions [80][81][82] in several flavors (B2-PLYP, B2GP-PLYP, B2π-PLYP, and PBE0-DH, see Table S2 in the Supporting Information) using toluene as solvent for the COSMO module. Whereas the TDA-PBE0/def2-TZVP//PBE0-D3(BJ)/def2-TZVP method (starting point) gives a value of 4.09 eV for this molecule, the use of B2-PLYP slightly improves it to 3.98 eV, with the other methods providing values roughly above it, and this trend holds for TPA and pCBP molecules too.…”

Describing excited states of [n]cycloparaphenylenes by hybrid and double-hybrid density functionals: from isolated to weakly interacting molecules

“…We will first study how the nature of the lowest singlet excited-state evolves with system size, employing Time-Dependent Density Functional Theory (TD-DFT), investigating next the changes when going from an isolated molecule to a weakly interacting dimer, taken at crystal structure. Due to the long-range nature of the latter interactions, we will systematically employ double-hybrid (last generation) density functionals [41], whose details are presented in the next section, together with hybrid and range-separated models, in an attempt to disentangle the subtle yet expectedly marked interplay between intra-and inter-molecular excitation energies.…”

Quadratic integrand double-hybrid made spin-component-scaled

“…[4][5][6][7] They introduce a fraction of nonlocal correlation computed according to the second-order perturbation theory (PT2) into a global-hybrid expression,…”