Performance Analysis and Optimization of Mixed-Reference Spin-Flip Time-Dependent Density Functional Theory (MRSF-TDDFT) for Vertical Excitation Energies and Singlet–Triplet Energy Gaps

Horbatenko, Yevhen; Lee, Seunghoon; Filatov, Michael; Choi, Cheol Ho

doi:10.1021/acs.jpca.9b07556

Cited by 45 publications

(58 citation statements)

References 71 publications

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“…As the current implementation of MRSF also utilizes the collinear formalism, it was shown that MRSF requires more exact exchange contribution (such as BHHLYP). 34 Therefore, all the calculations were carried out using the BH&HLYP. The effect of B3LYP on dynamics shall be also discussed later.…”

Section: Resultsmentioning

confidence: 99%

Impact of the Dynamic Electron Correlation on the Unusually Long Excited-State Lifetime of Thymine

Park

Lee

Huix‐Rotllant

et al. 2021

J. Phys. Chem. Lett.

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Relaxation of the photoexcited thymine in the gas-phase shows an unusually long excited-state lifetime, previously attributed to trapping in the absorbing excited state (S 2 -trapping mechanism).Here, we investigate this mechanism using the non-adiabatic molecular dynamics (NAMD) simulations combined with the recently developed Mixed Reference Spin-Flip (MRSF)-TDDFT method. We show that the S 2 -trapping was an artifact caused by an insufficient account of electron correlation in the electronic structure methodologies used for NAMD. The current work predicts instead an S 1 -trapping mechanism with two lifetimes, τ 1 =30±1 fs and τ 2 =6.1±0.035 ps, quantitatively consistent with time-resolved experiments. Upon excitation to S 2 (ππ * ) state, thymine undergoes an ultrafast internal conversion from S 2 → S 1 (ca. 30 fs) and resides 1 around the minimum on the S 1 (n O π * ) surface slowly decaying to the ground state (ca. 6.1 ps). The S 2 →S 1 internal conversion is mediated by bond length alternation stretching, which repeatedly passes through a newly found planar conical intersection region. The subsequent S 1 →S 0 internal conversion occurs through several conical intersections involving slow puckering motions of the pyrimidine ring.

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Section: Resultsmentioning

confidence: 99%

Impact of the Dynamic Electron Correlation on the Unusually Long Excited-State Lifetime of Thymine

Park

Lee

Huix‐Rotllant

et al. 2021

J. Phys. Chem. Lett.

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“…329,330 There have been various attempts to find a more theoretically appealing solution to this conundrum by adding additional determinants to the excitation space in order to restore Ŝ2 symmetry. 27 Methods developed along these lines include a fully spin-complete version of SF-TDDFT, 329 which adds the minimal number of additional determinants needed to obtain Ŝ2 eigenstates (based on the equation-ofmotion formalism), 77 and also a "mixed-reference" spin-flip (MRSF) approach, which uses a combination of high-spin and low-spin S + 1 reference states to generate target states with spin S. [331][332][333][334][335][336] Although the MRSF-TDDFT excitation manifold is not formally spin-complete, in practice the spin contamination is very small. 331 The analytic gradient 334 and nonadiabatic derivative couplings 335 for MRSF-TDDFT have recently been formulated, facilitating nonadiabatic molecular dynamics simulations.…”

Section: Conical Intersectionsmentioning

confidence: 99%

Density Functional Theory for Electronic Excited States

Herbert¹

2022

Preprint

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This chapter provides a basic introduction to excited-state extensions of density functional theory (DFT), including time-dependent (TD-)DFT in both its linear-response and its explicitly time-dependent formulations. As applied to the Kohn-Sham DFT ground state, linear-response theory affords an eigenvaluetype problem for the excitation energies in a basis of singly-excited Slater determinants, and is widely known simply as "TDDFT" despite its frequency-domain formulation. This form of TDDFT is the mostly widely-used quantum-chemical method for excited states, due to a favorable combination of low cost and reasonable accuracy. The chapter surveys the accuracy of linear-response TDDFT, which is generally more sensitive to the details of the exchange-correlation functional as compared to ground-state DFT, and also describes some known systemic problems exhibited by this approach. Some of those problems can be corrected on a case-by-case basis using orbital-optimized, excited-state self-consistent field (SCF) calculations, in what is known as excited-state Kohn-Sham theory or a "∆SCF" procedure, a class of methods that includes restricted open-shell Kohn-Sham theory. Recent successes of these approaches are highlighted, including double excitations and core-level excitations. Finally, explicitly time-dependent (or "real-time") TDDFT involves propagation of the molecular orbitals in time following an external perturbation, according to the Kohn-Sham analogue of the time-dependent Schrödinger equation. The time-dependent approach has been used to model strong-field electron dynamics, and in the weak-field limit it provides a route to broadband spectra based on the time evolution of the dipole moment function. This is useful for describing high-energy excitations (as in x-ray spectroscopy) and in systems where the density of states is high, as demonstrated by a few examples.

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“…12,38,39 Although some NMD simulations using SF-TDDFT have been reported using this approach, 21,39-46 a more reliable remedy is to remove the spin contamination directly. This can be done either exactly, by construction, [9][10][11][12] or else approximately, [47][48][49][50][51] but these procedures are not yet in widespread use.…”

Section: B Sf-tddftmentioning

confidence: 99%

Nonadiabatic dynamics with spin-flip vs linear-response time-dependent density functional theory: A case study for the protonated Schiff base C5H6NH2+

Zhang

Herbert

2021

The Journal of Chemical Physics

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Nonadiabatic trajectory surface hopping simulations are reported for trans-C5H6NH + 2 , a model of the rhodopsin chromophore, using the augmented fewest-switches algorithm. Electronic structure calculations were performed using time-dependent density functional theory (TDDFT) in both its conventional linear-response (LR) and its spin-flip (SF) formulations. In the SF-TDDFT case, spin contamination in the low-lying singlet states is removed by projecting out the lowest triplet component during iterative solution of the TDDFT eigenvalue problem. The results show that SF-TDDFT is able to correctly describe the photoisomerization of trans-C5H6NH + 2 , with favorable comparison to previous studies using multireference electronic structure methods. In contrast, conventional LR-TDDFT affords qualitatively different photodynamics due to an incorrect excited-state potential surface near the Franck-Condon region. In addition, the photochemistry (involving pre-twisting of the central double bond) appears to be different for SF-and LR-TDDFT, which may be a consequence of different conical intersection topographies afforded by these two methods. The present results contrast with previous surface-hopping studies suggesting that the LR-TDDFT method's incorrect topology around S1/S0 conical intersections is immaterial to the photodynamics.

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Performance Analysis and Optimization of Mixed-Reference Spin-Flip Time-Dependent Density Functional Theory (MRSF-TDDFT) for Vertical Excitation Energies and Singlet–Triplet Energy Gaps

Cited by 45 publications

References 71 publications

Impact of the Dynamic Electron Correlation on the Unusually Long Excited-State Lifetime of Thymine

Impact of the Dynamic Electron Correlation on the Unusually Long Excited-State Lifetime of Thymine

Density Functional Theory for Electronic Excited States

Nonadiabatic dynamics with spin-flip vs linear-response time-dependent density functional theory: A case study for the protonated Schiff base C5H6NH2+

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