Accurate Ionization Potentials, Electron Affinities, and Band Gaps from the?LH22t Range-Separated Local Hybrid Functional: No Tuning Required

The optimal tuning (OT) of range-separated hybrid (RSH) functionals has been proposed as the currently most accurate DFT-based way to compute the relevant quantities required for charge-transfer processes in organic chromophores used in organic photovoltaics and related fields. The main drawback of OT-RSHs is that the system-specific tuning of the range-separation parameter is not size-consistent. It therefore also lacks transferability, e.g., when considering processes involving orbitals not involved in the tuning or for reactions between different chromophores. Here we show that the recently reported ?LH22t range-separated local hybrid functional provides ionization energies, electron affinities, and fundamental gaps on par with OT-RSH treatments, approaching the quality of GW results, without any need for system-specific tuning. This holds from relevant organic chromophores of varying sizes all the way to atomic electron affinities. ?LH22t also gives excellent outer-valence quasiparticle spectra and is a generally accurate functional for both main-group and transition-metal energetics, as well as for a variety of excitation types. Range-separated local hybrid functionals are suggested as promising new quantum-chemical tools in molecular electronics.

Automated summary

The recently reported ?LH22t range-separated local hybrid functional can provide results for ionization energies, electron affinities, and fundamental gaps that are comparable to OT-RSH methods, approaching the quality of GW results, without the need for system-specific tuning. This functional also gives excellent outer-valence quasiparticle spectra and is accurate for various excitation types, making it a promising new tool in molecular electronics.