Introduction of a New Theory for the Calculation of Magnetic Coupling Based on Spin–Flip Constricted Variational Density Functional Theory. Application to Trinuclear Copper Complexes which Model the Native Intermediate in Multicopper Oxidases

Zhekova, Hristina R.; Seth, Michel; Ziegler, Tom

doi:10.1021/ct200141v

Cited by 42 publications

(38 citation statements)

References 49 publications

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“…52,53 Because time-dependent DFT contains only single excitations, SF-DFT has been limited to computing only singlet/triplet or doublet/quartet energy gaps directly. [65][66][67][68] However, as we have already demonstrated, with the help of a HDVV Hamiltonian, J constants can be computed from single spin-flip calculations. SF-DFT is no exception, and as a simple example, we also report SF-DFT results in Table III using the 50% exact exchange functional recommended in the original SF-DFT paper.…”

Section: B Comparison Of 1sf Methods To Experimentsmentioning

confidence: 99%

Computational quantum chemistry for single Heisenberg spin couplings made simple: Just one spin flip required

Mayhall

Head‐Gordon

2014

The Journal of Chemical Physics

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We highlight a simple strategy for computing the magnetic coupling constants, J, for a complex containing two multiradical centers. On the assumption that the system follows Heisenberg Hamiltonian physics, J is obtained from a spin-flip electronic structure calculation where only a single electron is excited (and spin-flipped), from the single reference with maximum Ŝz, M, to the M - 1 manifold, regardless of the number of unpaired electrons, 2M, on the radical centers. In an active space picture involving 2M orbitals, only one β electron is required, together with only one α hole. While this observation is extremely simple, the reduction in the number of essential configurations from exponential in M to only linear provides dramatic computational benefits. This (M, M - 1) strategy for evaluating J is an unambiguous, spin-pure, wave function theory counterpart of the various projected broken symmetry density functional theory schemes, and likewise gives explicit energies for each possible spin-state that enable evaluation of properties. The approach is illustrated on five complexes with varying numbers of unpaired electrons, for which one spin-flip calculations are used to compute J. Some implications for further development of spin-flip methods are discussed.

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Section: B Comparison Of 1sf Methods To Experimentsmentioning

confidence: 99%

Computational quantum chemistry for single Heisenberg spin couplings made simple: Just one spin flip required

Mayhall

Head‐Gordon

2014

The Journal of Chemical Physics

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“…Indeed, DFT emerged in the early 2000s as a powerful technique, particularly when used in combination with the hybrid B3LYP functional [86,87] and the Broken-Symmetry (BS) Noodleman's approach [88,89], for satisfactory simulations of magnetic properties. This is true not only in the case of d-transition metal systems [82,83,[90][91][92][93][94][95][96][97][98][99][100][101][102][103][104], but also for actinide-containing molecules [105][106][107]. It is worth noting that actinide-based SMMs are multiconfigurational systems, and the use of the monodeterminantal approach with DFT is a subject of debate [63,[108][109][110].…”

Section: Introductionmentioning

confidence: 99%

DFT Investigations of the Magnetic Properties of Actinide Complexes

2019

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Over the past 25 years, magnetic actinide complexes have been the object of considerable attention, not only at the experimental level, but also at the theoretical one. Such systems are of great interest, owing to the well-known larger spin–orbit coupling for actinide ions, and could exhibit slow relaxation of the magnetization, arising from a large anisotropy barrier, and magnetic hysteresis of purely molecular origin below a given blocking temperature. Furthermore, more diffuse 5f orbitals than lanthanide 4f ones (more covalency) could lead to stronger magnetic super-exchange. On the other hand, the extraordinary experimental challenges of actinide complexes chemistry, because of their rarity and toxicity, afford computational chemistry a particularly valuable role. However, for such a purpose, the use of a multiconfigurational post-Hartree-Fock approach is required, but such an approach is computationally demanding for polymetallic systems—notably for actinide ones—and usually simplified models are considered instead of the actual systems. Thus, Density Functional Theory (DFT) appears as an alternative tool to compute magnetic exchange coupling and to explore the electronic structure and magnetic properties of actinide-containing molecules, especially when the considered systems are very large. In this paper, relevant achievements regarding DFT investigations of the magnetic properties of actinide complexes are surveyed, with particular emphasis on some representative examples that illustrate the subject, including actinides in Single Molecular Magnets (SMMs) and systems featuring metal-metal super-exchange coupling interactions. Examples are drawn from studies that are either entirely computational or are combined experimental/computational investigations in which the latter play a significant role.

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“…In the framework of density functional theory (DFT), the J constant is generally extracted from high spin (HS) and broken symmetry (BS) state energy computations [23][24][25][26][27][48][49][50][51][52][53][54][55]. This technique introduced initially by Noodlemann et al [56][57][58] was successfully used in combination with the hybrid B3LYP Dedicated to Professor Vincenzo Barone and published as part of the special collection of articles celebrating his 60th birthday.…”

Section: Introductionmentioning

confidence: 99%

A relativistic DFT study of magnetic exchange coupling in ketimide bimetallic uranium(IV) complexes

et al. 2012

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International audienceMagnetic exchange couplings in bis(ketimide) binuclear UIV/UIV complexes [Cp′2UCl]2(μ-ketimide) diuranium(IV) and [(C5H5)2(Cl)An]2(μ-ketimide) (Cp′ = C5Me4Et; ketimide = N=CMe-(C6H4)-MeC=N) have been investigated computationally using relativistic density functional theory (DFT) combined with the broken symmetry (BS) approach. Using the B3LYP hybrid functional, the BS ground state of these UIV/UIV 5f 2-5f 2 complexes has been found of lower energy than the high spin (HS) quintet state, indicating an antiferromagnetic character (estimated coupling constant |J| < 5 cm−1) which has not yet been evidenced unambiguously experimentally. On the contrary, the BP86 GGA functional overestimates greatly the antiferromagnetic character of the complexes (|J| > 100 cm−1). As recently reported for para-bis(imido) [(C5H5)3U]2(μ-imido) uranium(V) complex, spin polarization is mainly responsible for the antiferromagnetic coupling through the π-network orbital pathway within the bis(ketimide) bridge. Furthermore, spin polarization is exalted by the combined roles of the 5f metal orbitals and of the π-conjugated ketimide bridging ligand which permit electronic communication between the two uranium atoms albeit separated by a distance of the order of 10 Å. The MO analysis clarifies which MOs contribute to the antiferromagnetic coupling in the binuclear complexes under consideration and brings to light the 5f orbitals driving contribution

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Introduction of a New Theory for the Calculation of Magnetic Coupling Based on Spin–Flip Constricted Variational Density Functional Theory. Application to Trinuclear Copper Complexes which Model the Native Intermediate in Multicopper Oxidases

Cited by 42 publications

References 49 publications

Computational quantum chemistry for single Heisenberg spin couplings made simple: Just one spin flip required

Computational quantum chemistry for single Heisenberg spin couplings made simple: Just one spin flip required

DFT Investigations of the Magnetic Properties of Actinide Complexes

A relativistic DFT study of magnetic exchange coupling in ketimide bimetallic uranium(IV) complexes

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