Periodic Density Functional Calculations in Order to Assess the Cooperativity of the Spin Transition in Fe(phen)2(NCS)2

Paulsen, Hauke

doi:10.3390/magnetochemistry2010014

Cited by 17 publications

(45 citation statements)

References 61 publications

(78 reference statements)

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“…The first attempt to obtain Γ in this way from first principles calculations [12] yielded a value that was twice as large as the value derived from experiment. A possible explanation for this overestimation of Γ is based on the limited number of configurations that were used in ref.…”

Section: Periodic Density Functional Calculationsmentioning

confidence: 99%

“…1) has been chosen as a complex that is most suitable to test the methods described above. It certainly is one of the most intensively studied SCO complex and also one of the very few that have been studied by periodic DFT calculations [12,[19][20][21][22][23][24]. High precision crystal structures are available for the HS and LS phases at different temperatures down to 15 K [25,26].…”

Section: Ising-like Modelsmentioning

confidence: 99%

“…A possible explanation for this overestimation of Γ is based on the limited number of configurations that were used in ref. [12]. If only few configurations are accessible, only large values of E(c) on the right side of Equation (6) are contributing and, consequently, the interaction parameter Γ will be overestimated.…”

Section: Periodic Density Functional Calculationsmentioning

confidence: 99%

“…This equation can be either used to determine parameters like ∆E HL , ∆S HL and Γ by fitting a measured γ HS (T) curve [11] or to predict such a curve by means of calculated parameters, e.g. from DFT calculations [10][11][12].…”

Section: Slichter-drickamer Modelmentioning

confidence: 99%

“…[6][7][8][9]). While much work has been done to predict transition temperatures, far less effort went into calculating the character (gradual or abrupt) of the thermally induced spin transition [10][11][12]. For technical applications, however, the abruptness of the transition and the width of the thermal hysteresis is as important as a suitable transition temperature.…”

Section: Introductionmentioning

confidence: 99%

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Cooperativity of Spin Crossover Complexes: Combining Periodic Density Functional Calculations and Monte Carlo Simulations

Kreutzburg

Hübner

Paulsen

2017

Preprint

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Abstract:The total enthalpies of the 16 different spin configurations that can be realized in the unit cell of the archetype spin crossover complex [Fe(phen) 2 (NCS) 2 ] (phen=1,2-phenanthroline) were calculated applying periodic density functional theory combined with the Hubbard model and the Grimme-D2 dispersion correction (DFT+U/D2). The obtained enthalpy differences between the individual spin configurations were used to determine spin couplings of an Ising-like model and subsequent Monte Carlo simulations for this model allowed to estimate the phenomenological interaction parameter Γ of the Slichter-Drickamer model, which is commonly used to describe the cooperativity of the spin transition. The calculational procedure described here, which led to an estimate of about 3 kJ mol −1 for Γ, in good agreement with experiment, may be used to predict from first principles how modifications of spin crossover complexes can change the character of the spin transition from gradual to abrupt and vice versa.

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Section: Periodic Density Functional Calculationsmentioning

confidence: 99%

Section: Ising-like Modelsmentioning

confidence: 99%

Section: Periodic Density Functional Calculationsmentioning

confidence: 99%

Section: Slichter-drickamer Modelmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Cooperativity of Spin Crossover Complexes: Combining Periodic Density Functional Calculations and Monte Carlo Simulations

Kreutzburg

Hübner

Paulsen

2017

Preprint

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Origin of Bistability in the Butyl‐Substituted Spirobiphenalenyl‐Based Neutral Radical Material

Fumanal

Novoa

Ribas‐Ariño

2017

Chemistry A European J

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One of the most remarkable bistable materials reported so far is made of π dimers of a butyl-substituted spirobiphenalenyl boron radical (butyl-SBP). The phase transition of this material, which is accompanied by changes in its optical, conductive, and magnetic properties, occurs with a hysteretic loop 25 K wide centered at 335 K. Herein, a computational study is presented aimed at deciphering the origin of this hysteresis. The phase transition of butyl-SBP consists of a spin transition of the constituent π dimers coupled with an order-disorder transition involving the butyl chains linked to the nitrogen atoms of the superimposed phenalenyl rings of the π dimer. Below 335 K, the terminal methyl group of the butyl chains adopts a gauche conformation with respect to the methylene unit bonded to the nitrogen atom. Above 335 K, the methyl group is in an anti conformation and exhibits dynamic disorder. The gauche→anti conformational rearrangement triggers the spin transition of the π dimers and is responsible for the hysteretic behavior of butyl-SBP. Specifically, the onset of the phase transition in the heating mode, and thus, the width of the hysteresis loop, are governed by the high energy cost and strong structural cooperative effects associated with this conformational change. Our results show that coupling a spin switch with a conformational switch in a molecular crystal provides a promising strategy in the design of new bistable materials.

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Deposition of the Spin Crossover Fe^II–Pyrazolylborate Complex on Au(111) Surface at the Molecular Level

Montenegro-Pohlhammer

Sánchez-de-Armas

Calzado

2020

Chemistry A European J

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The interaction at the molecular level of the spin‐crossover (SCO) FeII((3,5‐(CH3)2Pz)3BH)2 complex with the Au(111) surface is analyzed by means of rPBE periodic calculations. Our results show that the adsorption on the metallic surface enhances the transition energy, increasing the relative stability of the low spin (LS) state. The interaction indeed is spin‐dependent, stronger for the low spin than the high spin (HS) state. The different strength of the Fe ligand field at low and high temperature manifests on the nature, spatial extension and relative energy of the states close to the Fermi level, with a larger metal–ligand hybridization in the LS state. This feature is of relevance for the differential adsorption of the LS and HS molecules, the spin‐dependent conductance, and for the differences found in the corresponding STM images, correctly reproduced from the density of states provided by the rPBE calculations. It is expected that this spin dependence will be a general feature of the SCO molecule–substrate interaction, since it is rooted in the different ligand field of Fe site at low and high temperatures, a common hallmark of the FeII SCO complexes. Finally, the states involved in the LIESST phenomenon has been identified through NEVPT2 calculations on a model reaction path. A tentative pathway for the photoinduced LS→HS transition is proposed, that does not involve the intermediate triplet states, and nicely reproduces both the blue laser wavelength required for the activation, and the wavelength of the reverse HS → LS transition.

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Periodic Density Functional Calculations in Order to Assess the Cooperativity of the Spin Transition in Fe(phen)2(NCS)2

Cited by 17 publications

References 61 publications

Cooperativity of Spin Crossover Complexes: Combining Periodic Density Functional Calculations and Monte Carlo Simulations

Cooperativity of Spin Crossover Complexes: Combining Periodic Density Functional Calculations and Monte Carlo Simulations

Origin of Bistability in the Butyl‐Substituted Spirobiphenalenyl‐Based Neutral Radical Material

Deposition of the Spin Crossover Fe^II–Pyrazolylborate Complex on Au(111) Surface at the Molecular Level

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Periodic Density Functional Calculations in Order to Assess the Cooperativity of the Spin Transition in Fe(phen)2(NCS)2

Cited by 17 publications

References 61 publications

Cooperativity of Spin Crossover Complexes: Combining Periodic Density Functional Calculations and Monte Carlo Simulations

Cooperativity of Spin Crossover Complexes: Combining Periodic Density Functional Calculations and Monte Carlo Simulations

Origin of Bistability in the Butyl‐Substituted Spirobiphenalenyl‐Based Neutral Radical Material

Deposition of the Spin Crossover FeII–Pyrazolylborate Complex on Au(111) Surface at the Molecular Level

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Product

Resources

About

Deposition of the Spin Crossover Fe^II–Pyrazolylborate Complex on Au(111) Surface at the Molecular Level