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Accurate prediction of inverted singlet-triplet excited states using self-consistent spin-opposite perturbation theory

Nhan Tri Tran, Hoang Thanh Nguyen, Lan Nguyen Tran

Abstract

The violation of Hund's rule, resulting in an inverted singlet-triplet (INVEST) gap, represents a paradigm shift in photophysics with major implications for OLED technology. INVEST molecules facilitate barrierless reverse intersystem crossing, theoretically permitting 100\% internal quantum efficiency without thermal activation. However, accurately predicting negative singlet-triplet energy gaps typically demands prohibitive computational costs. In this study, we evaluate the efficacy of our recently developed one-body Møller-Plesset perturbation theory (OBMP2) and its spin-opposite variant (O2BMP2) as efficient alternatives. Benchmarking against 30 INVEST molecules reveals that O2BMP2, with appropriate spin-opposite scaling, achieves the accuracy of ADC(3) and EOM-CCSD. Furthermore, with the possibility of reducing computational complexity to $N^4$, O2BMP2 provides a robust balance of accuracy and efficiency, making it suitable for the high-throughput screening of next-generation INVEST materials.

Accurate prediction of inverted singlet-triplet excited states using self-consistent spin-opposite perturbation theory

Abstract

The violation of Hund's rule, resulting in an inverted singlet-triplet (INVEST) gap, represents a paradigm shift in photophysics with major implications for OLED technology. INVEST molecules facilitate barrierless reverse intersystem crossing, theoretically permitting 100\% internal quantum efficiency without thermal activation. However, accurately predicting negative singlet-triplet energy gaps typically demands prohibitive computational costs. In this study, we evaluate the efficacy of our recently developed one-body Møller-Plesset perturbation theory (OBMP2) and its spin-opposite variant (O2BMP2) as efficient alternatives. Benchmarking against 30 INVEST molecules reveals that O2BMP2, with appropriate spin-opposite scaling, achieves the accuracy of ADC(3) and EOM-CCSD. Furthermore, with the possibility of reducing computational complexity to , O2BMP2 provides a robust balance of accuracy and efficiency, making it suitable for the high-throughput screening of next-generation INVEST materials.
Paper Structure (6 sections, 10 equations, 6 figures, 5 tables)

This paper contains 6 sections, 10 equations, 6 figures, 5 tables.

Table of Contents

  1. Introduction
  2. Theory and computational details
  3. Results and discussion
  4. INVEST SET A
  5. INVEST SET B
  6. Conclusion

Figures (6)

  • Figure 1: 20 molecules in the INVEST set B adopted from Ref pollice2024rational.
  • Figure 2: Mean absolute deviations (MADs) of the lowest singlet and triplet excitation energies and the resulting singlet–triplet energy gap
  • Figure 3: HOMO and LUMO of first four molecules in the INVEST set B calculated using O2BMP2/1.7.
  • Figure 4: MADs and STDs relative to EOM-CCSD (upper panel) and ADC(3) (lower panel).
  • Figure 5: Pearson correlation between different methods with EOM-CCSD (upper panel) and ADC(3) (lower panel).
  • ...and 1 more figures