The Superexchange mechanism in crystalline compounds. The case of KMF3(M=Mn, Fe, Co, Ni) perovskites.

2021 ◽  
Author(s):  
Fabien Pascale ◽  
Philippe D’Arco ◽  
Valentina Lacivita ◽  
Roberto Dovesi
Keyword(s):  
Closed Shell ◽  
Basis Set ◽  
Equilibrium Geometry ◽  
Density Functionals ◽  
Teller Distortion ◽  
Hartree Fock ◽  
Jahn Teller ◽  
Crystal Code ◽  
First Time ◽  
Jahn Teller Distortion

Abstract The ferromagnetic and antiferromagnetic wavefunctions of four KMF3 (M= Mn, Fe, Co and Ni) perovskites have been obtained quantum-mechanically with the CRYSTAL code, by using the Hartree-Fock (HF) Hamiltonian and three flavours of DFT (PBE, B3LYP and PBE0) and an all-electron Gaussian type basis set. In the Fe and Co cases, with d6and d7occupation, the Jahn-Teller distortion of the cubic cell is as large as 0.12 Å. Various features of the superexchange interaction energies (SIE), namely additivity, dependence on the M-M distance, on the MFM̂ angle, and on the adopted functional, are explored. The contribution to SIE by the Coulomb, exchange and kinetic energy terms is analyzed. It is shown that, when using density functionals, SIE clearly correlates with the amount of exact (Hartree-Fock) exchange in the functional. The effect of SIE on the equilibrium geometry and volume of the unit cell is discussed, and it is shown that the key quantity is the spin polarization of the (closed shell) F ions along the M-F-M path. The effect of this magnetic pressure is evaluated quantitatively for the first time.

COMPARATIVE INVESTIGATION OF THE EFFECT OF TYPE OF DENSITY FUNCTIONAL IN THE DETERMINATION OF GEOMETRICAL PARAMETERS IN A Cu COMPLEX

2013 ◽  
Vol 12 (07) ◽  
pp. 1350066 ◽  
Author(s):  
JABER JAHANBIN SARDROODI ◽  
ALIREZA RASTKAR ◽  
NEGAR RAD YOUSEFNIA ◽  
JAFAR AZAMAT
Keyword(s):  
Density Functional ◽  
Comparative Investigation ◽  
Basis Set ◽  
Basis Sets ◽  
Geometrical Parameters ◽  
Teller Distortion ◽  
Hartree Fock ◽  
Jahn Teller ◽  
Jahn Teller Distortion

The effects of short-range electron correlation, long-range electron exchange, local and nonlocal parts of density, higher order gradients of density, and adding some percentage of Hartree–Fock exchange to the functional on the prediction of geometrical parameters were investigated. A copper complex namely 1,2-bis(1,4,7-triaza-1-cyclononyl) ethane copper (II) with Jahn–Teller distortion in octahedral geometry was used to evaluate the performance of 50 commonly available density functionals. The standard 3-21G basis set was used for all light elements, while pseudo potential LANL2DZ was used for the copper atom. The best bond lengths and bond angles were obtained using M05-2x and OP functionals respectively. Also in order to more accurate survey the performance of B3LYP, we used this functional with two all-electron basis sets (6-31G and 3-21G) and three basis sets involving effective core potentials (LANL2DZ/3-21G, LANL2DZ, and LACVP).

The Interplay of Open-Shell Spin-Coupling and Jahn-Teller Distortion in Benzene Radical Cation Probed by X-ray Spectroscopy

2020 ◽  
Author(s):  
Marta L. Vidal ◽  
Michael Epshtein ◽  
Valeriu Scutelnic ◽  
Zheyue Yang ◽  
Tian Xue ◽  
...  
Keyword(s):  
High Harmonic ◽  
Open Shell ◽  
Spin Coupling ◽  
High Symmetry ◽  
Teller Distortion ◽  
Spectral Window ◽  
X Ray ◽  
Jahn Teller ◽  
X Ray Absorption ◽  
Jahn Teller Distortion

We report a theoretical investigation and elucidation of the x-ray absorption spectra of neutral benzene and of the benzene cation. The generation of the cation by multiphoton ultraviolet (UV) ionization as well as the measurement of<br>the carbon K-edge spectra of both species using a table-top high-harmonic generation (HHG) source are described in the companion experimental paper [M. Epshtein et al., J. Phys.<br>Chem. A., submitted. Available on ChemRxiv]. We show that the 1sC -> pi transition serves as a sensitive signature of the transient cation formation, as it occurs outside of the spectral window of the parent neutral species. Moreover, the presence<br>of the unpaired (spectator) electron in the pi-subshell of the cation and the high symmetry of the system result in significant differences relative to neutral benzene in the spectral features associated with the 1sC ->pi* transitions. High-level calculations using equation-of-motion coupled-cluster theory provide the interpretation of the experimental spectra and insight into the electronic structure of benzene and its cation.<br>The prominent split structure of the 1sC -> pi* band of the cation is attributed to the interplay between the coupling of the core -> pi* excitation with the unpaired electron<br>in the pi-subshell and the Jahn-Teller distortion. The calculations attribute most of<br>the splitting (~1-1.2 eV) to the spin coupling, which is visible already at the Franck-Condon structure, and estimate the additional splitting due to structural relaxation to<br>be around ~0.1-0.2 eV. These results suggest that x-ray absorption with increased resolution might be able to disentangle electronic and structural aspects of the Jahn-Teller<br>effect in benzene cation.<br>

Jahn-Teller Effect in Hexahydroxocuprate(II) Complexes

1995 ◽  
Vol 60 (9) ◽  
pp. 1429-1434
Author(s):  
Martin Breza
Keyword(s):  
Hydrogen Bonding ◽  
Quantum Chemical ◽  
Potential Surface ◽  
Hydroxyl Group ◽  
Chemical Calculation ◽  
Teller Distortion ◽  
Jahn Teller ◽  
Jahn Teller Effect ◽  
Extremal Values ◽  
Jahn Teller Distortion

Using semiempirical CNDO-UHF method the adiabatic potential surface of 2[Cu(OH)6]4- complexes is investigated. The values of vibration and vibronic constants for Eg - (a1g + eg) vibronic interaction attain extremal values for the optimal O-H distance. The Jahn-Teller distortion decreases with increasing O-H distance. The discrepancy between experimentally observed elongated bipyramid of [Cu(OH)6]4- in Ba2[Cu(OH)6] and the compressed one obtained by quantum-chemical calculation is explainable by hydrogen bonding of the axial hydroxyl group.

Unveiling the role of Mn-interstitial defect and particle size on the Jahn-Teller distortion of the LiMn2O4 cathode material

2021 ◽  
Vol 490 ◽  
pp. 229519
Author(s):  
Renier Arabolla Rodríguez ◽  
Nelcy Della Santina Mohallem ◽  
Manuel Avila Santos ◽  
Demetrio A. Sena Costa ◽  
Luciano Andrey Montoro ◽  
...  
Keyword(s):  
Particle Size ◽  
Cathode Material ◽  
Teller Distortion ◽  
Interstitial Defect ◽  
Jahn Teller ◽  
Limn2o4 Cathode ◽  
Jahn Teller Distortion

OBSERVATION OF THE ESR FOR HIGH-Tc SUPERCONDUCTORS Bi-Sr-Ca-Cu-O

1989 ◽  
Vol 03 (04) ◽  
pp. 355-359 ◽  
Author(s):  
S.L. YUAN ◽  
B.H. HOU ◽  
S.Z. JIN ◽  
W. WANG ◽  
G.G. ZHENG ◽  
...  
Keyword(s):  
Superconducting Transition ◽  
Teller Distortion ◽  
High Tc ◽  
Spin Resonance ◽  
Jahn Teller ◽  
Zero Resistance ◽  
Magnetic Ions ◽  
Preliminary Study ◽  
Perpendicular Component ◽  
Jahn Teller Distortion

The preliminary study on the electron spin resonance (ESR) for the Bi-Sr-Ca-Cu-O system with different superconducting transition temperatures has been made at room temperature. It is found that the Lande factor g-values are increased with increasing zero resistance temperature T c0 but width between peaks ΔH pp of the ESR spectrum decreased with increasing T c0 . These might be attributed to the spin-orbit coupling of the magnetic ions and the Jahn-Teller distortion in the perpendicular component.

Experimental Evidence for a Jahn-Teller Distortion in AuCl3

2005 ◽  
Vol 117 (41) ◽  
pp. 6904-6908 ◽  
Author(s):  
Ian J. Blackmore ◽  
Adam J. Bridgeman ◽  
Neil Harris ◽  
Mark A. Holdaway ◽  
John F. Rooms ◽  
...  
Keyword(s):  
Experimental Evidence ◽  
Teller Distortion ◽  
Jahn Teller ◽  
Jahn Teller Distortion
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