On the Heisenberg behaviour of magnetic coupling in the manganese dimer

Negodaev, Igor; Graaf, Coen de; Caballol, Rosa

doi:10.1016/j.cplett.2008.05.011

Cited by 33 publications

(42 citation statements)

References 39 publications

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“…On the other hand, taking into account the difference in the basis sets, the present CASPT2 results look consistent with the data by Wang and Chen 45 R e = ͓3.79͔ Å, D e = ͓810͔ cm −1 and Negodaev et al 50 dramatic effect: In fact, it reverses the situation producing, in most cases, repulsive potentials. At the second order, it strongly ͑four times͒ overestimates the binding energy and predicts too short bond length.…”

Section: B Resultssupporting

confidence: 92%

“…They also obtained a regular ordering of excited states with ascending spin, and deduced the value of J close to the matrix isolation result. Negodaev et al 50 were the first to apply the nonperturbative MR technique, the configuration interaction ͑CI͒ approach, to calculate the splittings between the spin states. 47 for the very similar study͒.…”

Section: Introductionmentioning

confidence: 99%

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Electronic structure and spin coupling of the manganese dimer: The state of the art of ab initio approach

Buchachenko

Chałasiński

Szczȩśniak

2010

The Journal of Chemical Physics

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A thorough ab initio study of the Mn(2) dimer in its lowest electronic states that correlate to the ground Mn((6)S)+Mn((6)S) dissociation limit is reported. Performance of multireference methods is examined in calculations of the fully spin-polarized S=5((11) summation operator(+) (u)) state against the recent accurate single-reference coupled cluster CCSD(T) results [A. A. Buchachenko, Chem. Phys. Lett. 459, 73 (2008)]. The detailed comparison reveals a serious disagreement between the multireference configuration interaction (MRCI) and related nonperturbative results on the one hand and the complete active space perturbation theory (CASPT) calculations on the other. A striking difference found in the CASPT results of the second and third orders indicates poor perturbation expansion convergence. It is shown that a similar problem has affected most of the previous calculations performed using CASPT2 and similar perturbative approximations. The composition of the active space in the reference multiconfigurational self-consistent field calculations, the core correlation contribution, and basis set saturation effects are also analyzed. The lower spin states, S=0-4, are investigated using the MRCI method. The results indicate a similar dispersion binding for all the spin states within the manifold related to the closed 4s shells, which appears to screen and suppress the spin coupling between the half-filled 3d atomic shells. On this premise, the full set of model potentials is built by combining the accurate reference CCSD(T) interaction potential for S=5 and the MRCI spin-exchange energies for the S<5 states. This approach leads to the value of 550 cm(-1) as a lower bound for the (1) summation (+) (g) ground-state dissociation energy. The spin-exchange energies themselves are found to comply with the simple Heisenberg model. The effective spin-coupling parameter J is estimated as -3.9 cm(-1), a value roughly 2.5 times smaller in magnitude than those measured in the inert gas cryogenic matrices. Compressing of the Mn(2) dimer in the matrix cage is suggested as the prime cause of this disagreement.

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Section: B Resultssupporting

confidence: 92%

Section: Introductionmentioning

confidence: 99%

Electronic structure and spin coupling of the manganese dimer: The state of the art of ab initio approach

Buchachenko

Chałasiński

Szczȩśniak

2010

The Journal of Chemical Physics

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“…However, previous theoretical studies on system 1a and related complexes show that the deviations obtained in DDCI are in general small. This suggest that the deviations to the Heisenberg behavior observed with CASPT2 are not physically grounded, as previously concluded for other complexes …”

Section: Resultsmentioning

confidence: 49%

Improving the calculation of magnetic coupling constants in MRPT methods

et al. 2014

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The magnetic coupling in transition metal compounds with more than one unpaired electron per magnetic center has been studied with multiconfigurational perturbation theory. The usual shortcomings of these methodologies (severe underestimation of the magnetic coupling) have been overcome by describing the Slater determinants with a set of molecular orbitals that maximally resemble the natural orbitals of a high-level multiconfigurational reference configuration interaction calculation. These orbitals have significant delocalization tails onto the bridging ligands and largely increase the coupling strengths in the perturbative calculation.

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“…Assignment of the ground state of neutral Mn 2 dimer is challenging and is still under debate. The lowest total energy state of the dimer was found to possess the spin multiplicity of 11 if computed using density functional theory methods, [49][50][51] whereas Hartree-Fock based studies [52][53][54][55][56][57] have predicted a singlet 1 Σ g + state to be the ground state of Mn 2 . The latter is in agreement with an early experimental ESR study which predicted a singlet antiferromagnetic state for the dimer.…”

Section: Calibration Of Computational Methodsmentioning

confidence: 99%

Photoelectron spectra and structure of the Mnn− anions (n = 2–16)

Gutsev

Weatherford

Ramachandran

et al. 2015

The Journal of Chemical Physics

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Photoelectron spectra of the Mnn(-) anion clusters (n = 2-16) are obtained by anion photoelectron spectroscopy. The electronic and geometrical structures of the anions are computed using density functional theory with generalized gradient approximation and a basis set of triple-ζ quality. The electronic and geometrical structures of the neutral Mnn clusters have also been computed to estimate the adiabatic electron affinities. The average absolute difference between the computed and experimental vertical detachment energies of an extra electron is about 0.2 eV. Beginning with n = 6, all lowest total energy states of the Mnn(-) anions are ferrimagnetic with the spin multiplicities which do not exceed 8. The computed ionization energies of the neutral Mnn clusters are in good agreement with previously obtained experimental data. According to the results of our computations, the binding energies of Mn atoms are nearly independent on the cluster charge for n > 6 and possess prominent peaks at Mn13 and Mn13(-) in the neutral and anionic series, respectively. The density of states obtained from the results of our computations for the Mnn(-) anion clusters show the metallic character of the anion electronic structures.

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On the Heisenberg behaviour of magnetic coupling in the manganese dimer

Cited by 33 publications

References 39 publications

Electronic structure and spin coupling of the manganese dimer: The state of the art of ab initio approach

Electronic structure and spin coupling of the manganese dimer: The state of the art of ab initio approach

Improving the calculation of magnetic coupling constants in MRPT methods

Photoelectron spectra and structure of the Mnn− anions (n = 2–16)

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