Multireference Density Functional Theory with Generalized Auxiliary Systems for Ground and Excited States

Chen, Zehua; Zhang, Du; Jin, Ye; Yang, Yang; Su, Neil Qiang; Yang, Weitao

doi:10.1021/acs.jpclett.7b01864

Cited by 25 publications

(52 citation statements)

References 42 publications

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“…104 As an effective concept to address the NCE in wavefunction theory, the multi-reference strategy is now gaining more and more attention in DFT. [120][121][122] Despite quite promising with these notable advances, the multi-reference DFT is not yet ready for general purpose. Alternatively, we are more interested in the development of the fifth rung correlation models within the single-reference framework.…”

Section: Sie/nce Dilemma In Dftmentioning

confidence: 99%

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On the top rung of Jacob's ladder of density functional theory: Toward resolving the dilemma of SIE and NCE

Zhang

2020

WIREs Comput Mol Sci

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According to the classification of Jacob's Ladder proposed by Perdew, density functional approximations (DFAs) on the top (fifth) rung add the information of the unoccupied Kohn-Sham orbitals, which hold the promise to enter the heaven of chemical accuracy. In other words, we expect that a much higher accuracy with a broader applicability than the existing DFAs would eventually be achieved on the fifth rung. Nonetheless, Jacob's Ladder itself does not offer a recipe for how to manipulate the unoccupied Kohn-Sham orbitals on the construction of a successful fifth rung DFA. In this article, we briefly review two successful types of the fifth rung DFAs, that is, random-phase approximation (RPA) and doubly hybrid approximation (DHA). The limitations of RPA and DHA will be introduced in the context of the so-called self-interaction error (SIE)/nondynamic correlation error (NCE) dilemma in the world of density functional theory. We propose the development strategy for DHAs to address the general concern about the future of advanced DFAs on the fifth rung. We share our experience here, based on the relevant efforts recently made by the authors and their co-workers, aiming to resolve the SIE/NCE dilemma and to extend the applicability of DHAs from the chemistry of the main group elements to that of the transition metals.

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Section: Sie/nce Dilemma In Dftmentioning

confidence: 99%

“…As an effective concept to address the NCE in wavefunction theory, the multi‐reference strategy is now gaining more and more attention in DFT 120–122 . Despite quite promising with these notable advances, the multi‐reference DFT is not yet ready for general purpose.…”

Section: Challengesmentioning

confidence: 99%

On the top rung of Jacob's ladder of density functional theory: Toward resolving the dilemma of SIE and NCE

Zhang

2020

WIREs Comput Mol Sci

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“…To treat molecules like 4CzTPN, one should consider a methodological modification like to incorporate the frequency dependence in E XC [226][227][228] or to implement the multi-configurational therapy. 17,229,230…”

Section: Charge Transfer Triplet Statementioning

confidence: 99%

Triplet Tuning: A Novel Family of Non-Empirical Exchange–Correlation Functionals

Lin

Voorhis

2019

J. Chem. Theory Comput.

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In the framework of density functional theory (DFT), the lowest triplet excited state, T 1 , can be evaluated using multiple formulations, the most straightforward of which are unrestricted DFT (UDFT) and time-dependent DFT (TDDFT). Assuming the exact exchangecorrelation (XC) functional is applied, UDFT and TDDFT provide identical energies for T 1 (E T ), which is also a constraint that we require our XC functionals to obey. However, this condition is not satisfied by most of the popular XC functionals, leading to inaccurate predictions of low-lying, spectroscopically and photochemically important excited states, such as T 1 and the lowest singlet excited state (S 1 ). Inspired by the optimal tuning strategy for frontier orbital energies [T. Stein, L. Kronik, and R. Baer, J. Am. Chem. Soc. 131, 2818 (2009)], we proposed a novel and non-empirical prescription of constructing an XC functional in which the agreement between UDFT and TDDFT in E T is strictly enforced. Referred to as "triplet tuning", our procedure allows us to formulate the XC functional on a case-by-case basis using the molecular structure as the exclusive input, without fitting to any experimental data. The first triplet tuned XC functional, TT-ωPBEh, is formulated as a long-range-corrected (LRC) hybrid of Perdew-Burke-Ernzerhof (PBE) and Hartree-Fock (HF) functionals [M. A. Rohrdanz, K. M. Martins, and J. M. Herbert, J. Chem. Phys. 130, 054112 (2009)] and tested on four sets of large organic molecules. Compared to existing functionals, TT-ωPBEh manages to provide 1 arXiv:1806.00317v3 [physics.chem-ph] 15 Jan 2019more accurate predictions for key spectroscopic and photochemical observables, including but not limited to E T , the optical band gap (E S ), the singlet-triplet gap (∆E ST ), and the vertical ionization potential (I ⊥ ), as it adjusts the effective electron-hole interactions to arrive at the correct excitation energies. This promising triplet tuning scheme can be applied to a broad range of systems that were notorious in DFT for being extremely challenging.

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“…Motivated by the ability of DFT to account for dynamic correlation effects, the RASCI wave function has been mixed with DFT exchange‐correlation functionals following the same spirit as other WFT‐DFT hybrid schemes 73–89 . Concretely, the new approach (RASCI‐ sr DFT or simply RAS‐ sr DFT) 44 combines RASCI with short‐range DFT energy through the range separation of the Coulomb operator (Equation ()), as initially introduced by Savin 73,90 and exploited as a computationally affordable strategy to include dynamic correlation in a variety of multi‐reference approaches 91–95 …”

Section: Recovering Dynamic Correlationmentioning

confidence: 99%

Restricted active space configuration interaction methods for strong correlation: Recent developments

Casanova

2021

WIREs Comput Mol Sci

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In this review we outline the theory and recent progress of the restricted active space configuration interaction (RASCI) methodology within the hole and particle approximation. The RASCI is a single reference approach based on the splitting of the orbital space in different subsets, in which the target CI space is expressed by the concomitant number of electrons and empty orbitals in each subspace. Initially, the method was born as a spin complete version of the spin‐flip ansatz able to deal with any number of unpaired electrons. Since then, the method has experienced several improvements related to its theoretical foundations, its efficient implementation, in the characterization of RASCI wave functions, and in the calculation of molecular properties. It has shown to be especially suitable for the characterization of medium to large molecular diradicals and polyradicals, and to the study of photophysical processes involving open‐shell species and/or multiexcitonic states, like in the singlet fission reaction. But, despite this success, several limitations emerge from the sever truncation of the excitation operator, which might translate into inaccurate relative energies between different regions of the potential energy surface, and overestimated (or underestimated) excitation energies. These errors are associated with the lack of dynamic correlation, which has motivated the development and implementation of various improvements based on multi‐reference perturbation theory and to blend the RASCI wave function with density functional theory through range separation of electron–electron interactions. Finally, we discuss some of the properties available from RASCI wave functions and give potential future developments. This article is categorized under: Electronic Structure Theory > Ab Initio Electronic Structure Methods Software > Quantum Chemistry Quantum Computing > Theory Development

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Multireference Density Functional Theory with Generalized Auxiliary Systems for Ground and Excited States

Cited by 25 publications

References 42 publications

On the top rung of Jacob's ladder of density functional theory: Toward resolving the dilemma of SIE and NCE

On the top rung of Jacob's ladder of density functional theory: Toward resolving the dilemma of SIE and NCE

Triplet Tuning: A Novel Family of Non-Empirical Exchange–Correlation Functionals

Restricted active space configuration interaction methods for strong correlation: Recent developments

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