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

Dávid Mester,Mihály Kállay

doi:10.1021/acs.jctc.1c00422

Abstract

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.

Highlights

Nowadays, the density functional theory (DFT) is one of the most popular tools in quantum chemistry, it is still challenging to select the most suitable density functional approximations for particular purposes
To preserve compatibility with our RS-DHs, the default parameters of λ = 0.7 and μ = 0.5 bohr−1 obtained for the same training set in ref 70 were retained
It means that the lower weight of one of the contributions can be compensated by the higher weight of the other ones

Summary

INTRODUCTION

The density functional theory (DFT) is one of the most popular tools in quantum chemistry, it is still challenging to select the most suitable density functional approximations for particular purposes. An excitedstate DH analogue can be defined relying on it.[67] The first spin-scaled variants of the genuine ansatz were considered by Schwabe and Goerigk,[68] while the first LR-corrected DHs were proposed by the same group.[69] Our RS-DH functionals,[70] where both the exchange and correlation contributions are range-separated, were recently published These methodological developments significantly improve the performance of the functionals for excited states, only a few comprehensive studies[71,72] can be found on the comparison of the most recent methods. The SOS variant can be defined in this case, and the computational requirements can be reduced to the ground-state calculations.[89]

Spin-Scaled Ansatz for the Two-Parameter RS

RESULTS

CONCLUSIONS

■ ACKNOWLEDGMENTS

■ REFERENCES