A refined model of the double exchange phenomenon: Test on the stretched N2+ molecule

Taratiel, David; Guihéry, Nathalie

doi:10.1063/1.1786913

Cited by 16 publications

(15 citation statements)

References 25 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…In particular, the value of the exchange integral J 31,32 We have seen in the previous subsection that the model spectra present the same qualitative features as the ab initio spectrum at the experimental geometry.…”

Section: 9mentioning

confidence: 69%

Ab initiostudy of the CE magnetic phase in half-doped manganites: Purely magnetic versus double exchange description

2008

Self Cite

View full text Add to dashboard Cite

The leading electronic interactions governing the local physics of the CE phase of half-doped manganites are extracted from correlated ab initio calculations performed on an embedded cluster.The electronic structure of the low-energy states is dominated by double exchange configurations and O-2p σ to Mn-3d charge transfer configurations. The model spectra of both a purely magnetic non-symmetric Heisenberg Hamiltonian involving a magnetic oxygen and two non-symmetric double exchange models are compared to the ab initio one. While a satisfactory agreement between the Heisenberg spectrum and the calculated one is obtained, the best description is provided by a double exchange model involving excited non-Hund atomic states. This refined model not only perfectly reproduces the spectrum of the embedded cluster in the crystal geometry, but also gives a full description of the local double-well potential energy curve of the ground state (resulting from the interaction of the charge localized electronic configurations) and the local potential energy curves of all excited states ruled by the double exchange mechanism.

show abstract

Section: 9mentioning

confidence: 69%

Ab initiostudy of the CE magnetic phase in half-doped manganites: Purely magnetic versus double exchange description

2008

Self Cite

View full text Add to dashboard Cite

show abstract

“…We investigate the dependence of t on the total spin S , in order to test the approximate relation (4). The detailed analysis of the low‐energy spectrum of DE systems presented by Guihéry and colleagues 29, 30 confirmed the validity of the Anderson–Hasegawa model, although additional terms were introduced in the model to improve the overall agreement between model Hamiltonians and the ab initio spectrum. Such analysis is beyond the scope of the present work and will be the subject of future investigations.…”

Section: Introductionmentioning

confidence: 70%

Hopping matrix elements from first‐principles studies of overlapping fragments: Double exchange parameters in manganites

Stoyanova

Sousa

Graaf

et al. 2006

Int J of Quantum Chemistry

View full text Add to dashboard Cite

ABSTRACT:We recently developed a scheme for first-principles calculations of hopping matrix elements between localized states in extended systems. We apply the scheme to the determination of double exchange (DE) parameters in lightly hole-doped LaMnO 3 and electron-doped CaMnO 3 . DE is one of the important factors for understanding the properties of doped manganites. The calculations are based on the construction of wave functions for localized hole states or localized electron states for large embedded clusters. The wave functions of these clusters are expressed in terms of localized orbitals, obtained from calculations on smaller units, or "fragments," centered around a transition metal ion. The starting point of electronic states expressed in terms of localized orbital sets is conceptually attractive. It also allows for a rigorous treatment of local electron correlation and electronic relaxation effects. In the present study, the fragments are embedded [MnO 6 ] units. The large clusters contain either two or four Mn ions and all neighboring oxygen ligands. The results are compared with conventional embedded cluster calculations. In both compounds, the effective hopping matrix elements, or "double exchange" (DE) parameters, in the ab planes (in the Pbnm space group) are larger than along the c axes. We found nearly perfect agreement with the Anderson-Hasegawa model for the spin dependence of the DE parameters. Nearestneighbor parameters are more than one order of magnitude larger than next nearestneighbor parameters. In LaMnO 3 the DE in the ab planes is Ϸ Ϫ0.26 eV. If there were no Jahn-Teller distortion present in the material, it would have been twice as large. In CaMnO 3 , the corresponding nearest-neighbor DE parameter for hopping of a doped electron in the ab planes is only Ϸ Ϫ0.17 eV, due to the antiparallel spin coupling. However, since this interaction is much larger than the exchange coupling, we suggest that it induces local ferromagnetic clusters around the doped electrons.

show abstract

“…In Figure 7, the extracted parameters are plotted with respect to bond distance and compared against previouslyreported CAS-CI and CAS + DDCI results. 56 (Note that Taratiel's results use the ANO basis set in Molcas, while our results were calculated with cc-pvdz. ) The CAS-nSF-IP agrees best with CAS-CI, while RAS(h,p)-nSF-IP agrees best with CAS + DDCI.…”

Section: Parameter Extractionmentioning

confidence: 95%

A Combined Spin-Flip and IP/EA Approach for Handling Spin and Spatial Degeneracies: Application to Double Exchange Systems

Houck¹,

Mayhall²

2018

Preprint

View full text Add to dashboard Cite

<div>Many multiconfigurational systems, such as single-molecule magnets, are difficult to study using traditional computational methods due to the simultaneous existence of both spin and spatial degeneracies. In this work, a new approach termed n-spin-flip Ionization Potential/Electron Affinity (nSF-IP or nSF-EA) is introduced which combines the spin-flip method of Anna Krylov with particle-number changing IP/EA methods. We demonstrate the efficacy of the approach by applying it to the strongly-correlated N2+ as well as several double exchange systems. We also demonstrate that when these systems are well-described by a double exchange model Hamiltonian, only 1SF-IP/EA is required to extract the double exchange parameters and accurately predict energies for the low-spin states. This significantly reduces the computational effort for studying such systems. The effects of including additional excitations (using a RAS-nSF-IP/EA scheme) are also examined, with particular emphasis on hole and particle excitations.</div>

show abstract

A refined model of the double exchange phenomenon: Test on the stretched N2+ molecule

Cited by 16 publications

References 25 publications

Ab initiostudy of the CE magnetic phase in half-doped manganites: Purely magnetic versus double exchange description

Ab initiostudy of the CE magnetic phase in half-doped manganites: Purely magnetic versus double exchange description

Hopping matrix elements from first‐principles studies of overlapping fragments: Double exchange parameters in manganites

A Combined Spin-Flip and IP/EA Approach for Handling Spin and Spatial Degeneracies: Application to Double Exchange Systems

Contact Info

Product

Resources

About