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

Our recently presented
range-separated (RS) double-hybrid (DH)
time-dependent density functional approach [J. Chem. Theory
Comput. 17, 927 (2021)] is combined with spin-scaling
techniques. The proposed spin-component-scaled (SCS) and scaled-opposite-spin
(SOS) variants are thoroughly tested for almost 500 excitations including
the most challenging types. This comprehensive study provides useful
information not only about the new approaches but also about the most
prominent methods in the DH class. The benchmark calculations confirm
the robustness of the RS-DH ansatz, while several tendencies and deficiencies
are pointed out for the existing functionals. Our results show that
the SCS variant consistently improves the results, while the SOS variant
preserves the benefits of the original RS-DH method reducing its computational
expenses. It is also demonstrated that, besides our approaches, only
the nonempirical functionals provide balanced performance for general
applications, while particular methods are only suggested for certain
types of excitations.