Data-Driven Recommendation of Optimal Tuning Scheme for Range-Separated Hybrid Functionals in Solution-Phase UV/Vis...

Area of Science:

• Computational Chemistry
• Quantum Chemistry
• Spectroscopy

Background:

• Time-dependent density functional theory (TDDFT) with range-separated hybrid (RSH) functionals is cost-effective for predicting excited-state properties.
• Established gas-phase tuning procedures for the range-separation parameter (γ) do not directly translate to implicit solvent models like the polarizable continuum model (PCM).
• Lack of consensus exists on optimal γ-tuning methods for TDDFT calculations involving solvent effects.

Purpose of the Study:

• To evaluate and compare three γ-tuning methods (GPγT, PVγT, SVγT) for TDDFT calculations of solution-phase UV/vis absorption spectra.
• To determine the most effective γ-tuning strategy for accurate and efficient high-throughput excited-state property predictions in the presence of solvent effects.
• To benchmark the performance of tuned RSH functionals against existing methods like screened RSH-PCM and solvation-mediated tuning.

Main Methods:

• Creation of a diverse dataset of 937 molecules with experimental solution-phase UV/vis absorption spectra.
• Evaluation of gas-phase γ-tuning (GPγT), partial vertical γ-tuning (PVγT), and strict vertical γ-tuning (SVγT) for the ωPBEh functional.
• Benchmarking against optimally tuned screened range-separated hybrid (SRSH-PCM) and solvation-mediated tuning (sol-med-OT) procedures.

Main Results:

• Optimal γ-values from PVγT and SVγT are significantly smaller than those from GPγT, a trend consistent across the dataset.
• TDDFT calculations using PVγT and SVγT achieve superior performance compared to GPγT or default γ values.
• SVγT accurately captures the solution-phase asymptotic behavior and predicts charge-transfer excitations, outperforming other methods with comparable or lower computational cost.

Conclusions:

• Strict vertical γ-tuning (SVγT) is the most effective scheme for high-throughput UV/vis absorption spectrum calculations using ωPBEh in solution.
• PVγT and SVγT offer a data-driven, accurate, and computationally economical approach for excited-state property predictions.
• The findings provide a clear recommendation for optimizing TDDFT calculations in condensed phases.