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At least 973 records · Page 54Linked to original sources
PubMed2001

Molecular and electronic structure of [Mn(V)N(cyclam-acetato)]PF6. A combined experimental and DFT study.

From the reaction of Li(cyclam-acetate), MnCl(2).4H(2)O, and KPF(6) in methanol brown microcrystals of [Mn(III)Cl(cyclam-acetato)]PF(6) (1) were obtained in the presence of air (cyclam-acetic acid = 1,4,8,11-tetraazacyclotetradecane-1-acetic acid). The reaction of 1 in aqueous NH(3) solution with NaOCl produced blue crystals of [Mn(V)N(cyclam-acetato)]PF(6) (2). Complexes 1 and 2 were characterized by single-crystal X-ray crystallography, IR and Raman, electronic absorption, and (1)H, (13)C, and (15)N NMR spectroscopies. Their magnetochemistry as well as their electrochemistry have been investigated. The complexes [MnN(cyclam-acetato)](+/2+) were studied by theoretical calculations at the DFT and semiempirical levels in order to obtain more insight into the ground and excited states of the Mn(V)(triple bond)N unit. Structural and spectroscopic parameters were successfully calculated and compared to experiment. A pictorial description of the bonding has been developed.

Journal Article↗
PubMed1984

Iron electronic structure in oxyhemoglobin and carboxypeptidase digested derivatives.

Mössbauer experiments were performed on the oxy- derivatives of human hemoglobin and its products of digestion with carboxypeptidases. The hemoglobins were chemically enriched to 95% in 57Fe, and were free from hemochrome impurities. Spectra were taken at low temperatures in the presence and absence of a 5.0 T magnetic field. It was observed that the enzymatic digestions which remove residues at least 16 A from the iron of the nearest heme appear to modify the electronic environment of the metal.

Carboxypeptidase B↗
PubMed2004

The reaction of M(CO)3(Ph2PCH2CH2PPh2)(M = Fe, Ru) with parahydrogen: probing the electronic structure of reaction intermediates and the internal rearrangement mechanism for the dihydride products.

The photochemical reaction of Ru(CO)(3)(dppe) and Fe(CO)(3)(dppe)(dppe = Ph(2)PCH(2)CH(2)PPh(2)) with parahydrogen has been studied by in situ-photochemistry resulting in NMR spectra of Ru(CO)(2)(dppe)(H)(2) that show significant enhancement of the hydride resonances while normal signals are seen in Fe(CO)(2)(dppe)(H)(2). This effect is associated with a singlet electronic state for the key intermediate Ru(CO)(2)(dppe) while Fe(CO)(2)(dppe) is a triplet. DFT calculations reveal electronic ground states consistent with this picture. The fluxionality of Ru(CO)(2)(dppe)(H)(2) and Fe(CO)(2)(dppe)(H)(2) has been examined by NMR spectroscopy and rationalised by theoretical methods which show that two pathways for ligand exchange exist. In the first, the phosphorus and carbonyl centres interchange positions while the two hydride ligands are unaffected. A second pathway involving interchange of all three ligand sets was found at slightly higher energy. The H-H distances in the transition states are consistent with metal-bonded dihydrogen ligands. However, no local minimum (intermediate) was found along the rearrangement pathways.

Journal Article↗
PubMed2006

The electronic structure of transition metal dihelide dications.

Multi-reference configuration interaction (MRCI) calculations have been employed to characterize the low-lying states of first-row transition metal dihelide dications, He(2)TM(2+) (TM = Sc-Cu). The most important state-ordering principles were determined to be the occupation of the 4s orbital and orientation of the occupied 3d orbital. The ground states of all species are predicted to be of D(infinityh) symmetry arising from a 3d(n+1) electronic configuration. For excited states with singly occupied 4s or doubly occupied 3d(sigma) orbitals, bending to C(2v) symmetry typically lowers the energy and shortens the He-TM bond length. Coupled cluster singles and doubles with a perturbative treatment of triple excitations (CCSD(T)) results for ground state spectroscopic properties are in agreement with the MRCI predicted trends.

Computer Simulation↗
PubMed2005

Thermodynamic properties of molecular borane phosphines, alane amines, and phosphine alanes and the [BH(4)(-)][PH(4)(+)], [AlH(4)(-)][NH(4)(+)], and [AlH(4)(-)][PH(4)(+)] salts for chemical hydrogen storage systems from ab initio electronic structure theory.

The heats of formation for the molecules BH(3)PH(3), BH(2)PH(2), HBPH, AlH(3)NH(3), AlH(2)NH(2), HAlNH, AlH(3)PH(3), AlH(2)PH(2), HAlPH, AlH(4)(-), PH(3), PH(4), and PH(4)(+), as well as the diatomics BP, AlN, and AlP, have been calculated by using ab initio molecular orbital theory. The coupled cluster with single and double excitations and perturbative triples method (CCSD(T)) was employed for the total valence electronic energies. Correlation consistent basis sets were used, up through the augmented quadruple-zeta, to extrapolate to the complete basis set limit. Additional d core functions were used for Al and P. Core/valence, scalar relativistic, and spin-orbit corrections were included in an additive fashion to predict the atomization energies. Geometries were calculated at the CCSD(T) level up through at least aug-cc-pVTZ and frequencies were calculated at the CCSD(T)/aug-cc-pVDZ level. The heats of formation of the salts [BH(4)(-)][PH(4)(+)](s), [AlH(4)(-)][NH(4)(+)](s), and [AlH(4)(-)][PH(4)(+)](s) have been estimated by using an empirical expression for the lattice energy and the calculated heats of formation of the two component ions. The calculations show that both AlH(3)NH(3)(g) and [AlH(4)(-)][NH(4)(+)](s) can serve as good hydrogen storage systems that release H(2) in a slightly exothermic process. In addition, AlH(3)PH(3) and the salts [AlH(4)(-)][PH(4)(+)] and [BH(4)(-)][PH(4)(+)] have the potential to serve as H(2) storage systems. The hydride affinity of AlH(3) is calculated to be -70.4 kcal/mol at 298 K. The proton affinity of PH(3) is calculated to be 187.8 kcal/mol at 298 K in excellent agreement with the experimental value of 188 kcal/mol. PH(4) is calculated to be barely stable with respect to loss of a hydrogen to form PH(3).

Journal Article↗
PubMed2005

Photodissociation of HI and DI: testing models for electronic structure via polarization of atomic photofragments.

The photodissociation dynamics of HI and DI are examined using time-dependent wave-packet techniques. The orientation and alignment parameters aQ(K) (p) are determined as a function of photolysis energy for the resulting ground-state I(2P(3/2)) and excited-state I(2P(1/2)) atoms. The aQ(K) (p) parameters describe the coherent and incoherent contributions to the angular momentum distributions from the A 1pi(1), a 3pi(1), and t 3sigma(1) electronic states accessed by perpendicular excitation and the a 3pi(0+) state accessed by a parallel transition. The outcomes of the dynamics based on both shifted ab initio results and three empirical models for the potential-energy curves and transition dipole moments are compared and contrasted. It is demonstrated that experimental measurement of the aQ(K) (p) parameters for the excitation from the vibrational ground state (upsilon=0) would be able to distinguish between the available models for the HI potential-energy curves and transition dipole moments. The differences between the aQ(K) (p) parameters for the excitation from upsilon=0 stand in sharp contrast to the scalar properties, i.e., total cross section and I* branching fraction, which require experimental measurement of photodissociation from excited vibrational states (upsilon>0) to distinguish between the models.

Journal Article↗
PubMedDate not supplied

[Electron-conformational interactions at the active site of reduced bacterial cytochrome P450cam induced by a substrate and analysis of the electron structure of heme].

Magnetic circular dichroism (MCD) spectra in the Soret region (360-480 nm) of camphor-free and camphor-bound reduced bacterial cytochrome P450cam from Pseudomonas putida were recorded and analysed in the temperature range from 2 K to 290 K. The temperature dependences of the MCD intensity are qualitatively changed by binding of substrate to the enzyme. In the absence of camphor the linear increase of the MCD intensity with 1/T at T < 4.2 K gives evidence for degeneracy or near degeneracy of the ground electronic state. In the presence of substrate the degeneracy is removed and temperature profiles show saturation behaviour at T < 4.2 K and wavelength dependence of their high-temperature parts. The temperature profiles for the long-wavelength region of the Soret band have a maximum approximately at 15 K, whereas the MCD intensity increases in a monotonous manner up to saturation in the short-wavelength region. The wavelength dependence of temperature profiles gives evidence for the co-existence of two different forms of substrate-bound reduced P450cam. The following conclusions were obtained from a theoretical analysis of the temperature profiles. In the absence of substrate there are very small if any rhombic distortions at the heme iron, and a parameter D of axial zero-field splitting is negative (D = -8.3 cm-1 and -6.2 cm-1 for P450cam and P450LM2, respectively). In the presence of substrate the two forms of reduced P450cam have positive parameters D but of different values (D1 = 12 cm-1 and D2 = 28 cm-1), and there are large rhombic distortions at the heme iron. More than two-fold difference between the D values made it possible to isolate temperature-dependent contributions of the two enzyme forms from the total MCD spectra and to simulate the alterations of the MCD spectra with temperature for reduced P450cam in the presence of substrate. Taking into account the drastic effect of substrate binding on the ground electronic state of reduced P450cam one can suggest that substrate binding induces the transition of enzyme from an inactive to an active state.

Binding Sites↗
PubMed2000

Oxidation of iron: the relation between oxidation kinetics and oxide electronic structure

The test of the validity of the Fromhold-Cook theory of metal oxidation for the O2/Fe system in the tunnel regime is impeded by the growth of a passivating Fe2+/Fe3+ double layer at T</=150 degrees C. However, during an intermediate anneal step at 200 degrees C, the Fe3+ is reduced to Fe2+. The oxidation rate of this annealed layer is in agreement with the Fromhold-Cook theory. At room temperature, the ionic current is rate limiting. For T>150 degrees C, the thermionic emission of electrons is rate limiting for oxygen coverages larger than 13x10(15) atoms/cm(2).

Journal Article↗
PubMed2006

First-principles electronic structure study of the monoclinic crystal bismuth triborate BiB3O6.

Monoclinic BiB(3)O(6) is an excellent nonlinear optical material with many advantages compared to other borate crystals. The origins of the optical effects and the chemical stability of BiB(3)O(6) are studied with gradient-corrected hybrid B3PW density functional theory within the Gaussian-orbital-based CO-LCAO scheme. Including spin-orbit coupling, the B3PW hybrid functional provides an estimate of the indirect band gap of 4.29-4.99 eV closer to the experimental value of 4.3 eV than HF, LDA, or GGA. The crystal orbital overlap population to give a detailed first-principles analysis of chemical bonding and the density of optical absorptions by convoluting the occupied density of states and the virtual density of states have been calculated. Obvious Bi-O covalent bonds have been found with different energy ranges for 6s-2p and 6p-2p interactions. The reason that [BiO(4)](5-) units are mainly responsible for the optics of BiB(3)O(6) in the long-wavelength region is due to the electronic transfer from occupied O 2p to empty Bi 6p orbitals favored by the Bi-O covalent bonds. The relativistic and correlation effects lead to fundamental differences of the band structure, chemical bonds, and optical effects for BiB(3)O(6) compared with nonrelativistic and uncorrelated calculations.

Journal Article↗
PubMed2005

Electronic structure studies of the adenosylcobalamin cofactor in glutamate mutase.

Glutamate mutase (GM) is a cobalamin-dependent enzyme that catalyzes the reversible interconversion of L-glutamate and L-threo-3-methylaspartate via a radical-based mechanism. To initiate catalysis, the 5'-deoxyadenosylcobalamin (AdoCbl) cofactor's Co-C bond is cleaved homolytically to generate an adenosyl radical and Co2+ Cbl. In this work, we employed a combination of spectroscopic and computational tools to evaluate possible mechanisms by which the Co-C bond is activated for homolysis. Minimal perturbations to the electronic absorption (Abs), circular dichroism (CD), and magnetic CD (MCD) spectra of AdoCbl are observed upon formation of holoenzyme, even in the presence of substrate (or a substrate analogue), indicating that destabilization of the Co3+ Cbl "ground state" is an unlikely mechanism for Co-C bond activation. In contrast, striking alterations are observed in the spectroscopic data of the post-homolysis product Co2+ Cbl when bound to glutamate mutase in the presence of substrate (or a substrate analogue) as compared to unbound Co2+ Cbl. These enzymatic perturbations appear to most strongly affect the metal-to-ligand charge-transfer transitions of Co2+ Cbl, suggesting that the cofactor/active-site interactions give rise to a fairly uniform stabilization of the Co 3d orbitals. Remarkable similarities between the results obtained in this study and those reported previously for the related Cbl-dependent isomerase methylmalonyl-CoA mutase indicate that a common mechanism by which the cofactor's Co-C bond is activated for homolytic cleavage may be operative for all base-off/His-on Cbl-dependent isomerases.

Circular Dichroism↗
PubMed2005

Electronic structures of six-coordinate ferric porphyrin complexes with weak axial ligands: usefulness of 13C NMR chemical shifts.

1H NMR, (13)C NMR, and EPR spectra of six-coordinate ferric porphyrin complexes [Fe(Por)L2]ClO4 with different porphyrin structures are presented, where porphyrins (Por) are planar 5,10,15,20-tetraphenylporphyrin (TPP), ruffled 5,10,15,20-tetraisopropylporphyrin (TiPrP), and saddled 2,3,7,8,12,13,17,18-octaethyl-5,10,15,20-tetraphenylporphyrin (OETPP), and axial ligands (L) are weak oxygen ligands such as pyridine-N-oxide, substituted pyridine-N-oxide, DMSO, DMF, MeOH, THF, 2-MeTHF, and dioxane. These complexes exhibit the spin states ranging from an essentially pure high-spin (S = 5/2) to an essentially pure intermediate-spin (S = 3/2) state depending on the field strength of the axial ligands and the structure of the porphyrin rings. Reed and Guiset reported that the pyrrole-H chemical shift is a good probe to determine the spin state in the spin admixed S = 5/2,3/2 complexes (Reed, C. A.; Guiset, F. J. Am. Chem. Soc. 1996, 118, 3281-3282). In this paper, we report that the chemical shifts of the alpha- and beta-pyrrole carbons can also be good probes to determine the spin state because they have shown good correlation with those of the pyrrole-H or pyrrole-C(alpha). By putting the observed or assumed pyrrole-H or pyrrole-C(alpha) chemical shifts of the pure high-spin and pure intermediate-spin complexes into the correlation equations, we have estimated the carbon chemical shits of the corresponding complexes. The orbital interactions between iron(III) and porphyrin have been examined on the basis of these chemical shifts, from which we have found that both the d(xy)-a(2u) interaction in the ruffled Fe(T(i)PrP)L2+ and d(xy)-a(1u) interaction in the saddled Fe(OETPP)L2+ are quite weak in the high-spin and probably in the intermediate-spin complexes as well. Close inspection of the correlation lines has suggested that the electron configuration of an essentially pure intermediate-spin Fe(T(i)PrP)L2+ changes from (d(xy), d(yz))3(d(xy))1(d(z)2)1 to (d(xy))2(d(xz), d(yz))2(d(z)2)1 as the axial ligand (L) changes from DMF to MeOH, THF, 2-MeTHF, and then to dioxane. Although the DFT calculation has indicated that the highly saddled intermediate-spin Fe(OETPP)(THF)2+ should adopt (d(xy), d(yz))3(d(xy))1(d(z)2)1 rather than (d(xy))2(d(xz), d(yz))2(d(z)2)1 because of the strong d(xy)-a(1u) interaction (Cheng, R.-J.; Wang, Y.-K.; Chen, P.-Y.; Han, Y.-P.; Chang, C.-C. Chem. Commun. 2005, 1312-1314), our 13C NMR study again suggests that Fe(OETPP)(THF)2+ should be represented as (d(xy))2(d(xz), d(yz))2(d(z)2)1 because of the weak d(xy)-a(1u) interaction. The contribution of the S = 3/2 state in all types of the spin admixed S = 5/2,3/2 six-coordinate complexes has been determined on the basis of the (13)C NMR chemical shifts.

Carbon Isotopes↗
PubMed2004

Electronic structure of bent titanocene complexes with chelated dithiolate ligands.

Gas-phase photoelectron spectroscopy and density functional theory have been utilized to investigate the interactions between the p orbitals of dithiolate ligands and d orbitals of titanium in bent titanocene complexes as minimum molecular models of active site features of pyranopterin Mo/W enzymes. The compounds Cp(2)Ti(S-S) [where (S-S) is 1,2-ethenedithiolate (S(2)C(2)H(2)), 1, 1,2-benzenedithiolate (bdt), 2, or 1,3-propanedithiolate (pdt), 3, and Cp(-) is cyclopentadienyl] provide access to a formal 16-electron d(0) electronic configuration at the metal. A "dithiolate-folding-effect" involving an interaction of metal and sulfur orbitals is demonstrated in complexes with arene- and enedithiolates. This effect is not observed for the alkanedithiolate in complex 3.

Binding Sites↗
PubMed2002

Self-consistent green function approach for calculation of electronic structure in transition metals.

We present an approach for self-consistent calculations of the many-body Green function in transition metals. The distinguishing feature of our approach is the use of one-site approximation and the self-consistent quasiparticle wave function basis set obtained from the solution of the Schrödinger equation with a nonlocal potential. We analyze several sets of skeleton diagrams as generating functionals for the Green function self-energy, including GW and fluctuating exchange sets. Calculations for Fe and Ni revealed stronger energy dependence of the effective interaction and self-energy of the d electrons near the Fermi level compared to s and p electron states.

Journal Article↗
PubMed2001

Paramagnetic NMR investigations of high-spin nickel(II) complexes. Controlled synthesis, structural, electronic, and magnetic properties of dinuclear vs. mononuclear species.

New dissymmetric tertiary amines (N(3)SR) with varying N/S donor sets have been synthesized to provide mono- and dinuclear complexes. Acetate ions are used to complete the octahedral coordination sphere around nickel(II) atom(s). The facile conversion of mononuclear to dinuclear systems can be controlled to produce either mono- or dinuclear complexes from the same ligand. The dinuclear complex a(BPh(4))(2) ([Ni(2)(N(3)SSN(3))(OAc)(2)](BPh(4))(2)) has been characterized in the solid state by X-ray diffraction techniques as solvate: a(BPh(4))(2).(1/2)[5(CH(3)OH).(CH(3)CN).(CH(3)CH(2)OH)]. The two Ni atoms are six-coordinated and bridged by a disulfide group and two bidentate acetates. Magnetic susceptibility reveals a weak ferromagnetic exchange interaction between the two Ni atoms with J = 2.5(7) cm(-1). UV-vis studies suggest that the six-coordinated structure persists in solution. The (1)H NMR spectrum of a(BPh(4))(2) exhibits sharp significantly hyperfine shifted ligand signals. A complete assignment of resonances is accomplished by a combination of methods: 2D-COSY experiments, selective chemical substitution, and analysis of proton relaxation data. Proton isotropic hyperfine shifts are shown to originate mainly from contact interactions and to intrinsically contain a small J-magnetic coupling and/or zero-field splitting contribution. A temperature dependence study of longitudinal relaxation times indicates that a very unusual paramagnetic Curie dipolar mechanism is the dominant relaxation pathway in these weakly ferromagnetically spin-coupled dinickel(II) centers. The mononuclear nickel(II) analogue exhibits extremely broader (1)H NMR signals and only partial analysis could be performed. These data are consistent with a shortening of electronic relaxation times in homodinuclear compounds with respect to the corresponding mononuclear species.

Algorithms↗
PubMed2001

A theoretical approach to the influence of the macrocycle conformation on the molecular electronic structure in Mg-porphyrins.

Nonplanar saddled (sad) ruffled (ruf) and domed (dom) conformations of the Mg-porphyrin (MgP) macrocycle in several degrees of deformation have been computed. These symmetrical distortion modes were induced in unsubstituted macrocycle using molecular definitions for calculations which permits us to achieve a systematical variation of the nonplanarity varying only a convenient geometrical parameter of the molecule. Series of nonplanar macrocycles like those synthesized in previous works employing peripheral substitutions are obtained. The procedure here used to induce deformations gives the possibility of investigating the modulator role of the out-of-plane distortions on the geometry and electronic properties of the porphyrin avoiding additional influences due to the substituents or the surrounding protein scaffolding.

Chlorophyll↗
PubMed2003

Electronic structure and the Fermi surface of PuCoGa5 and NpCoGa5.

Using a relativistic linear augmented-plane-wave method, we clarify energy band structures and Fermi surfaces of recently discovered plutonium-based superconductor PuCoGa5 and the isostructural material NpCoGa5. For PuCoGa5, we find several cylindrical sheets of Fermi surfaces with large volume, similar to CeMIn5, while for NpCoGa5, the Fermi surfaces are found to be similar to those of UMGa5. These similarities are discussed based on the j-j coupling scheme, suggesting some hints for the superconducting mechanism in HoCoGa5-type f-electron compounds.

Journal Article↗
PubMed2004

Ortho-chalcogenostannates as ligands: syntheses, crystal structures, electronic properties, and magnetism of novel compounds containing ternary anionic substructures [M4(mu4-Se)(SnSe4)4]10- (M=Mn, Zn, Cd, Hg), 3(infinity)[[Hg4(mu4-Se)(SnSe4)3]6-], or 1(infinity)[[HgSnSe4]2-].

By reaction of K4[SnSe4].1.5 MeOH with CdCl2 or Hg(OAc)2 in water/methanol it was possible to prepare single crystals of four novel compounds that contain ternary anionic coordination oligomers and polymers: [K10(H2O)16(MeOH)(0.5)][M4(mu4-Se)(SnSe4)4] (4: M=Cd, 5: M=Hg), [K6(H2O)3][Hg4(mu4-Se)(SnSe4)3].MeOH (6), and K2[HgSnSe4] (7), which were structurally characterized by single-crystal X-ray diffraction. The optical absorption properties of the isostructural compounds 4 and 5, as well as those of the recently reported Zn (2) and Mn (3) analogues, were studied by UV-visible spectroscopy. These investigations showed the quaternary phases to have relatively small optical gaps for their molecular size (2.2-2.6 eV), which are similar to the excitation energies that were observed for mesostructured solids of the respective combination of elements. According to DFT investigations on the ternary anions, an experimentally observed difference between the absorption behavior of the d10 compounds 2, 4, and 5 and the open-shell d(5) compound 3 is in line with different characters of the frontier orbitals in the two cases. Both the calculations and a magnetic measurement on 3 demonstrated antiferromagnetic coupling between the mu(4)-Se-bridged Mn centers.

Journal Article↗
PubMed2006

Structural-electronic correlation in the first-order phase transition of [FeH2L2-Me](ClO4)2 (H2L2-Me = bis[((2-methylimidazol-4-yl)methylidene)-3- aminopropyl]ethylenediamine).

The synthesis and detailed study of the new mononuclear spin crossover complex [Fe(II)H2L(2-Me)](ClO4)2 (where H2L(2-Me) = bis[((2-methylimidazol-4-yl)methylidene)-3-aminopropyl]ethylenediamine) are reported. Variable-temperature magnetic susceptibility measurements show the occurrence of a steep spin crossover centered at 171.5 K with a hysteresis loop of ca. 5 K width (T(/2)(increasing) = 174 K and T(1/2)(decreasing) = 169 K, for increasing and decreasing temperatures, respectively). The crystal structure has been resolved for the high-spin (HS) and low-spin (LS) states at 200 and 123 K, respectively, revealing a crystallographic phase transition that occurs concomitantly to the spin crossover: at 200 K, the complex crystallizes in the monoclinic system, space group P2(1)/n, while the space group is P2(1) at 123 K. The mean Fe-N distances are shortened by 0.2 A, but the thermal spin crossover is accompanied by significant structural changes: the rearrangement of the central atom C12 of a six-membered chelate ring of [Fe(II)H2L(2-Me)]2+ to two positions (C12A and C12B) and, consequently, the lack of an inversion center at 123 K (P2(1) space group). Both HS and LS supramolecular structures involve all possible hydrogen bonds between imidazole and amine NH functions, and perchlorate anions; however, the HS supramolecular structure is a one-dimensional (1D) network, and the LS phase may better be described as a two-dimensional (2D) extended structure of A and B molecules. The structural phase transition of [FeH2L(2-Me)](ClO4)2 seems to trigger the steep and hysteretic spin crossover. Discontinuities in the temperature dependence of the Mössbauer parameters (isomer shift and quadrupole splitting) at the spin crossover temperature confirmed the occurrence of a structural phase transition. The experimental enthalpy and entropy variations were determined by differential scanning calorimetry (DSC) as 7.5 +/- 0.4 kJ/mol and 45 +/- 3 J K(-1) mol(-1), respectively. The regular solution theory was applied to the experimental data, yielding an interaction parameter of Gamma = 3.36 kJ/mol, which is larger than 2RT(1/2), which fulfills the condition for observing hysteresis.

Journal Article↗