• Bulletin of the Korean Chemical Society
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• v.35 no.4
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• pp.1061-1066
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• 2014

Time-dependent formulations of the reactive scattering theory based on the wavepacket correlation functions with the M${\phi}$ller wavepackets for the electronically nonadiabatic reactions are presented. The calculations of state-to-state reactive probabilities for the quasi-Jahn-Teller scattering model system were performed. The conical intersection (CI) effects are investigated by comparing the results of the two-surface nonadiabatic calculations and the single surface adiabatic approximation. It was found that the results of the two-surface nonadiabatic calculations show interesting features in the reaction probability due to the conical intersection. Single surface adiabatic calculations with extended Born-Oppenheimer approximation using simple wavepacket phase factor was found to be able to reproduce the CI effect semi-quantitatively, while the single surface calculations with the usual adiabatic approximation cannot describe the scattering process for the Jahn-Teller model correctly.

• Journal of the Korean Ceramic Society
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• v.35 no.8
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• pp.885-889
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• 1998

The temperature dependence of dc conductivity and magnetic properties of cation deficient {{{{ { {(LaMn) }_{1-λ }O }_{3 } }} systems has been investigated,. Above 160K the magnetic susceptibility of all samples followed the Curie-Weiss law. The Curie temperature decreased as the cation deficiency increased. This is due to a strong Jahn-Teller effect originated from electrons of {{{{ { Mn}^{3+ } }} In the case of samples annealed in air and oxygen at-mosphere the charge carriers responsible for conduction in the ferromagnetic regime below the Curie tem-perature are believed to have both magnetic and lattice characteristics. However the conduction carriers in the paramagnetic regime above the Curie temperature are though to be formed by hopping process of small polarons which were generated by assistance of the Jahn-Teller effect.

• Journal of the Korean Ceramic Society
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• v.36 no.1
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• pp.50-54
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• 1999

We have measured the x-ray photoemission spectroscopy of cation deficient La0.970Mn0.970O3 as a function of temperature. Detailed results on the chemical shifts and changes in Mn 2p and Lp 3d core levels due to variation of temperature have been obtained. The Mn 2p 3/2 and 1/2 main peaks and La 3d core spectrum shift to lower binding energy levels with increasing temperature. This XPS behavior is correlated with the strength of localization of Mn3+. The Jahn-Teller effect due to Mn3+ besides the conventional random potential effects is likely to localize charge carriers in La-.970Mn0.970O3.

• Journal of the Korean Magnetics Society
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• v.11 no.4
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• pp.151-156
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• 2001

Recently many studies on manganese oxides Ln$_{1-x}$A$_{x}$MnO$_3$(Ln=La, Pr, Nd lanthannide; A=Ca, Sr, Ba, Pb +2 ions) reported CMR properties. CMR have been also found in chalcogenide spinels. We have investigated that Ni ion substitutions for Fe ion have effects on CMR properties in chacogenide spinels Ni$_{x}$Fe$_{1-x}$Cr$_2$S$_4$. It was found that with increasing Ni concentration Jahn-Teller distortion was strengthened and Curie temperature T$_{c}$ was increased. CMR properties could be explained with Jahnl-Teller effect, half-metallic electronic structure, and the alignment of magnetic domain due to the strong magnetic field, which is different in that double exchange interactions dominate CMR properties in manganese oxides.

• Bulletin of the Korean Chemical Society
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• v.35 no.5
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• pp.1511-1515
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• 2014

The multiconfiguration second-order perturbation theory (CASPT2) and complete active space self-consistent field (CASSCF) methods were employed to calculate the geometries and energy levels for the low-lying electronic states of 1,3,5-$C_6H_3Cl{_3}^+$ ion. The CASPT2 values for the 1,3,5-$C_6H_3Cl{_3}^+$ ion were in reasonable agreement with the available experimental values. The current calculations augmented previous theoretical investigations on the ground state and assigned the low-lying excited electronic states of the 1,3,5-$C_6H_3Cl{_3}^+$ ion. The Jahn-Teller distortion in the excited electronic state for the 1,3,5-$C_6H_3Cl{_3}^+$ ion were reported for the first time.

• Bulletin of the Korean Chemical Society
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• v.25 no.6
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• pp.921-923
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• 2004

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.9 no.2
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• pp.245-250
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• 1999

The effect of cation substitution on the inonic conductivity was studied in $(Li_{0.5}La_{0.5})_{1-y}Sr_yTi_{1-x}Mn_xO_3$ system. In case of Sr substitution, the ionic conductivity abrubtly decreased over y=0.05. This may be caused by the decrease of lithium contents which contribute to lithium inonic conductivity. Jahn-Teller distortion as well as lattice parameter variation influenced the inonic conductivity in case of Mn substitution. A and B-site cations effects on the conductivities were found to be independent, and the ionic conductivity as high as $2.8{\times}10^{-2}$S/cm was obtained in x=0.0006 and y=0.05.

• Journal of the Korean Magnetics Society
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• v.9 no.3
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• pp.131-135
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• 1999

The electronic structures and properties of layered perovskite $LaSrMnO_4$ and $SR^2MnO_4$ have been determined using the local-density full potential Imearized augmented plane wave method. The total energy calculations show that the antiterromagnetic state has lower energy than the ferromagnetic state in $LaSrMnO_4$. The jahn-Teller distortion of Mn-O octahedron produces the energy gap and the $3z^2-r^2$ orbital ordering, which stabilizes 2 dimensional antiferromagnetis state.

• Journal of the Korean Vacuum Society
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• v.15 no.5
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• pp.527-533
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• 2006

Spinel $LiNi_xMn_{2-x}O_4$ thin films were synthesized up to x = 0.9 by a sol-gel method employing spin-coating. The Ni-substituted films were found to maintain cubic structure at low x but to exhibit tetragonal structure for $x{\geq}0.6$. Such cubic-tetragonal phase transition indicates that $Ni^{3+}(d7)$ ions with low-spin $(t_{2g}^6,e_g^1)$ state occupy the octahedral sites of the compound, thus being subject to the Jahn-Teller distortion. By x-ray photoelectron spectroscopy both $Ni^{2+}$ and $Ni^{3+}$ ions were detected. Optical properties of the $LiNi_xMn_{2-x}O_4$ films were investigated by spectroscopic ellipsometry (SE) in the visible?ultraviolet range. The measured dielectric function spectra by SE mainly consist of broad absorption structures attributed to charge-transfer (CT) transitions, $O^{2-}(2p){\rightarrow}Mn^{4+}(3d)$ for 1.9 $(t_{2g})$ and $2.8{\sim}3.0$ eV $(e_g)$ structures and $O^{2-}(2p){\rightarrow}Mn^{3+}(3d)$ for 2.3 $(t_{2g})$ and $3.4{\sim}3.6$ eV $(e_g)$ structures. Also, sharp absorption structures were observed at about 1.6, 1.7, and 1.9 eV, interpreted as due to d-d crystal-field transitions within the octahedral $Mn^{3+}$ ion. The strengths of these absorption structures are reduced by the Ni substitution. Rapid reduction of the CT transition strength involving the eg states for x = 0.6 is attributed to the reduced wavefunction overlap between the $e_g$ and the $O^{2-}(2p)$ states due to the tetragonal extension of the lattice constant by the Jahn-Teller effect.

• Bulletin of the Korean Chemical Society
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• v.20 no.6
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• pp.657-662
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• 1999

The variation of Jahn-Teller(J-T) distortion imposed on various metallo- tetraphenylporphyrins(MTPPS;M=ZnⅡ,PdⅡ,PtⅡ,and RhⅢ) has been investigated by time-resolved resonance Raman spectroscopy. B1g and B2g modes of the triplet(π,π*) states for the heavy-metal porphyrins exhibit the enhancement of their intensities compared with those of 3ZnⅢTPP, while the enhancement of phenyl internal mode is reduced. These results suggest that the J-T distortion becomes manifest as the metal size increases, and consequently the porphyrin-to-phenyl ring charge transfer in the excited triplet state is inhibited.