Comparative first-principles analysis of crystal field splitting, charge transfer energies and covalent effects for Cr2+ and Fe2+ ions in II–VI and III–V compounds

Configuration interaction cluster calculation can effectively reproduce the experimentally measured Ti L 23-edge absorption spectrum for the TiO6 cluster LaTiO3. A further investigation of the hybridization strength and charge-transfer energy effects on the multiplet structures suggests that LaTiO3 should be classified as an intermediate state between the charge-transfer and Mott–Hubbard regimes. Detailed temperature-dependent simulations of absorption spectra support the lifting of Ti t 2g orbital degeneracy and crystal field splitting. The spin–orbit coupling scenario is ruled out, even though 3d spin–orbit coupling can reproduce the experimental spectrum without including temperature. A combined polarization- and crystal-field-splitting-dependent analysis indicates asymmetric ΔCF–orbital interactions for the TiO6 cluster [Ti3+:3d 1(t 2g 1)], different from the orbital–lattice interactions reported for the NiO6 cluster [Ni3+:3d 7(t 2g 6 eg 1)]. The orbital polarization is defined in terms of the normalized electron occupancies in orbitals with xy and xz(yz) symmetries, and nearly complete orbital polarization (more than 75%) is observed, indicating strongly reduced orbital fluctuations due to the correlation effects. This is consistent with the density of states for titanates based on local density approximation plus dynamical mean-field theory calculations.

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Crystal field splitting in correlated systems with negative charge-transfer gap

Journal of Physics Condensed Matter ◽

10.1088/0953-8984/23/44/445601 ◽

2011 ◽

Vol 23 (44) ◽

pp. 445601 ◽

Cited By ~ 28

Author(s):

A V Ushakov ◽

S V Streltsov ◽

D I Khomskii

Keyword(s):

Charge Transfer ◽

Crystal Field ◽

Negative Charge ◽

Crystal Field Splitting ◽

Field Splitting ◽

Correlated Systems

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First-Principles Calculations of Energy Band for Wurtzite ZnO under Uniaxial Loading along [0001] Direction

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.633-634.324 ◽

2014 ◽

Vol 633-634 ◽

pp. 324-328

Author(s):

Li Xin Li ◽

Jun Liang Zhao ◽

Xue Mao Guan

Keyword(s):

Crystal Field ◽

First Principles ◽

Energy Gap ◽

Uniaxial Stress ◽

Uniaxial Loading ◽

Crystal Field Splitting ◽

First Principles Calculations ◽

Field Splitting ◽

Absolute Value ◽

Splitting Energy

First-principles calculations are carried out to analyze the variation of the energy gap and the absolute value of the crystal-field splitting energy of wurtzite zinc oxide under uniaxial loading along [0001] direction. The uniaxial loading in [0001] direction is predicted to be more effective to adjust the energy gap than applying the hydrostatic pressure, without changing the direct energy-gap nature. The top of the valence band is sensitive to the uniaxial stress, and the absolute value of the crystal-field splitting energy reaches the minimum when the uniaxial stress is about 2 GPa. The variation in electronic properties originates mainly from the relatively lower density of the valence electrons inc-axis direction.

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