Accurate Modeling of Spin-State Energetics in Spin-Crossover Systems with Modern Density Functional Theory

Ye, Shengfa; Neese, Frank

doi:10.1021/ic902365a

Cited by 218 publications

(235 citation statements)

References 51 publications

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“…[70][71][72][73][74] Nonetheless, in light of recent studies indicating the improved performance of the BP86 and TPSS functionals in describing transition metal containing systems, the geometries and energies of 2 were also calculated using these functionals and the larger TZVPP basis sets. [75][76][77] These results are shown in Table S4 which indicate that the B3LYP/6-31G* level of theory is reliable for the systems investigated in this study. The ''overlap population'' parameter listed in Tables S5 and S6 …”

Section: Methodssupporting

confidence: 57%

Catalytic Hydrogen Evolution by Fe(II) Carbonyls Featuring a Dithiolate and a Chelating Phosphine

et al. 2014

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Abstract:Two pentacoordinate mononuclear iron carbonyls of the form (bdt)Fe(CO)P 2 [bdt = benzene-1,2-dithiolate; P 2 = 1,1'-diphenylphosphinoferrocene (1) or methyl-2-{bis(diphenylphosphinomethyl)amino}acetate (2)] were prepared as functional, biomimetic models for the distal iron (Fe d ) of the active site of [FeFe]-hydrogenase. Xray crystal structures of the complexes reveal that, despite similar ν(CO) stretching band frequencies, the two complexes have different coordination geometries. In X-ray crystal structures, the iron center of 1 is in a distorted trigonal bipyramidal arrangement, and that of 2 is in a distorted square pyramidal geometry. Electrochemical investigation shows that both complexes catalyze electrochemical proton reduction from acetic acid at mild overpotential, 0.17 and 0.38 V for 1 and 2, respectively. Although coordinatively unsaturated, the complexes display only weak, reversible binding affinity towards CO(1 bar). However, ligand centered protonation by the strong acid, HBF 4 .OEt 2 , triggers quantitative CO uptake by 1 to form a dicarbonyl analogue [1(H)-CO] + that can be reversibly converted back to 1 by deprotonation using NEt 3 . Both crystallographically determined distances within the bdt ligand and DFT calculations suggest that the iron centers in both 1 and 2 are partially reduced at the expense of partial oxidation of the bdt ligand. Ligand protonation interrupts this extensive electronic delocalization between the Fe and bdt making 1(H) + susceptible to external CO binding.3

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Section: Methodssupporting

confidence: 57%

Catalytic Hydrogen Evolution by Fe(II) Carbonyls Featuring a Dithiolate and a Chelating Phosphine

et al. 2014

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“…These wavefunctions W MS 0 have different spin densities Q MS 0 ðrÞ that are related by Eq. (35). By construction, the ground-state wavefunction W s,0 of the noninteracting reference system and the ground-state wavefunction W 0 of the fully interacting system only share the same electron density.…”

Section: Interacting Energy Functional and Exchange-correlationmentioning

confidence: 99%

“…However, the functional E ], which is limited to spin densities corresponding to M S ¼ S. However, the spin densities Q MS corresponding to other eigenvalues of Ŝ z can be obtained from the scaling relation of Eq. (35). Again, it is important to realize that the fractional spin condition does not apply to E ðuÞ;ss…”

Section: Spin States In Ks-dftmentioning

confidence: 99%

“…[11,27,28]), a severe limitation are unsystematic errors in the prediction of the relative energies of different spin states. [29][30][31][32][33][34][35][36] Moreover, the spin density-which serves as an additional fundamental quantity in the spin-DFT formalism commonly employed for open-shell systems-is qualitatively incorrect in some cases. [15,[37][38][39] To make things even worse, the treatment of low-spin states usually requires the use of a broken-symmetry description, [40][41][42][43] which provides an unphysical spin density by construction (see, e.g., Refs.…”

Section: Introductionmentioning

confidence: 99%

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Spin in density‐functional theory

Jacob¹,

Reiher²

2012

Int J of Quantum Chemistry

213

219

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The accurate description of open-shell molecules, in particular of transition metal complexes and clusters, is still an important challenge for quantum chemistry. Although density-functional theory (DFT) is widely applied in this area, the sometimes severe limitations of its currently available approximate realizations often preclude its application as a predictive theory. Here, we review the foundations of DFT applied to open-shell systems, both within the nonrelativistic and the relativistic framework. In particular, we provide an in-depth discussion of the exact theory, with a focus on the role of the spin density and possibilities for targeting specific spin states. It turns out that different options exist for setting up Kohn-Sham DFT schemes for open-shell systems, which imply different definitions of the exchangecorrelation energy functional and lead to different exact conditions on this functional. Finally, we suggest possible directions for future developments.

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“…21,22 An extensive study of spin-crossover molecules using modern density functional theory, including meta-GGA and hybrid meta-GGA and double-hybrid functional, shows, generally speaking, relative energies of spin multiplici-ties are still challenging for DFT methods. 23 The spin density functional plus U (SDFT+U) 19,24 method was also applied to this system, but again obtaining the correct energy splitting required choosing U ≈ 2.5eV , much smaller than is believed to be relevant for Fe. 25,26 Diffusion Quantum Monte-Carlo method has also been applied to charged spin-crossover molecules, although direct comparisons to experiments are not currently feasible for charged systems.…”

mentioning

confidence: 99%

Density functional plus dynamical mean-field theory of the spin-crossover moleculeFe(phen)2(NCS)2

2015

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We study the spin-crossover molecule Fe(phen)2(NCS)2 using density functional theory (DFT) plus dynamical mean-field theory, which allows access to observables not attainable with traditional quantum chemical or electronic structure methods. The temperature dependent magnetic susceptibility, electron addition and removal spectra, and total energies are calculated and compared to experiment. We demonstrate that the proper quantitative energy difference between the high-spin and low-spin state, as well as reasonably accurate values of the magnetic susceptibility can be obtained when using realistic interaction parameters. Comparisons to DFT and DFT+U calculations demonstrate that dynamical correlations are critical to the energetics of the low-spin state. Additionally, we elucidate the differences between DFT+U and spin density functional theory (SDFT) plus U methodologies, demonstrating that DFT+U can recover SDFT+U results for an appropriately chosen on-site exchange interaction.

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Accurate Modeling of Spin-State Energetics in Spin-Crossover Systems with Modern Density Functional Theory

Cited by 218 publications

References 51 publications

Catalytic Hydrogen Evolution by Fe(II) Carbonyls Featuring a Dithiolate and a Chelating Phosphine

Catalytic Hydrogen Evolution by Fe(II) Carbonyls Featuring a Dithiolate and a Chelating Phosphine

Spin in density‐functional theory

Density functional plus dynamical mean-field theory of the spin-crossover moleculeFe(phen)2(NCS)2

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