Dissecting the ingredients of optimally tuned range-separated hybrid models for reliable description of non-adiabatic couplings.

Perusing the non-radiative processes requires a reliable prediction of non-adiabatic couplings (NACs) describing the interaction of two Born-Oppenheimer surfaces. In this regard, the development of appropriate and affordable theoretical methods that accurately account for the NAC terms between different excited-states is desirable. In this work, we develop and validate several variants of the optimally tuned range-separated hybrid functionals (OT-RSHs) for investigating NACs and related properties, such as excited states energy gaps and NAC forces, within the time-dependent density functional theory framework.

Toward highly efficient hyperfluorescence-based emitters through excited-states alignment using novel optimally tuned range-separated models.

Hyperfluorescence has recently been introduced as a promising strategy to achieve organic light-emitting diodes (OLEDs) with high color purity and enhanced stability. In this approach, fluorescent emitters (FEs) with strong and narrow band fluorescence are integrated in thin films containing sensitizers exhibiting thermally activated delayed fluorescence (TADF). Toward highly efficient hyperfluorescence-based emitters, the excited-states ordering of the FEs should be well-aligned.

Do any types of double-hybrid models render the correct order of excited state energies in inverted singlet-triplet emitters?

Organic emissive materials with the inverted singlet-triplet energy gaps, where in violation of Hund's multiplicity rule the lowest triplet excited-state is higher in energy than the lowest singlet excited-state, have recently come into the limelight. This unique feature is of important relevance, where the emitters meeting the singlet-triplet inversion have potential to usher in the next generation of organic light emitting diodes (OLEDs). Since experimental data in this context are currently sparse, necessity of the cost-effective theoretical tools able to provide reliable results seems to be evident.

Appraising spin-state energetics in transition metal complexes using double-hybrid models: accountability of SOS0-PBESCAN0-2(a) as a promising paradigm.

Double-hybrid (DH) approximations have entered into the limelight of density functional theory (DFT) computations of different properties; however, little is known regarding their accountability for spin-state energetics in transition metal complexes. In this work, taking high-level all-electron fixed-node diffusion Monte Carlo data as a reference, we present a survey of the applicability of parameterized and parameter-free DHs as well as their dispersion and non-local corrected versions for predicting the spin splitting energies of transition metal complexes collected from the literature and from our own proposals herein. Our proposed parameter-free DH based on the spin-opposite-scaled (SOS) scheme incorporating the Perdew-Burke-Ernzerhof (PBE) exchange and strongly constrained and appropriately normed (SCAN) correlation as well as high balanced fractions of nonlocal exchange and correlation without any additional correction, SOS0-PBESCAN0-2(a), is found to be superior for overall performance.