Electronic structure of low-spin ferric porphyrins: a single-crystal EPR and structural investigation of the influence of axial ligand orientation and the effects of pseudo-Jahn-Teller distortion

1987 ◽  
Vol 109 (11) ◽  
pp. 3301-3308 ◽  
Author(s):  
Robert Quinn ◽  
Joan Selverstone Valentine ◽  
Marianne P. Byrn ◽  
Charles E. Strouse
2004 ◽  
Vol 1 (7) ◽  
pp. 1641-1644 ◽  
Author(s):  
Mohammad E. Ghazi ◽  
P. D. Hatton

1987 ◽  
Vol 104 ◽  
Author(s):  
H. J. Von Bardeleben ◽  
D. Stievemard

ABSTRACTThe arsenic antisite-arsenic interstitial pair model for the stable configuration of the EL2 defect in GaAs has stimulated new experimental and theoretical studies, the results of which lead to additional support for this model. Recent theoretical studies, taking into account the effect of a Jahn Teller distortion of the T2 Asi levels have given an insight into the stability and the electronic structure of the defect pair. Further, ODENDOR studies have directly confirmed this model and allowed one to specify the lattice location and the charge state of the Asi ion. The pair structure of this defect implies a reconsideration of the charge states of the EL2 defect, as well as the origin of the optical absorption bands for which transitions on the Asi ion and intracenter bands have also to be considered. The model leads further to a description of the metastable configuration : an arsenic molecule at the gallium vacancy site, the electronic structure of which is calculated. The vacancy related defects, known from electron irradiation studies, are not detected in LEC grown GaAs as native defects.


2015 ◽  
Vol 29 (24) ◽  
pp. 1550136
Author(s):  
Shuying Zhong ◽  
Xueling Lei ◽  
Lang Zhou

Atomic and electronic structures of monovacancy (V1), divacancy (V2) and ring hexavacancy (V6) in crystalline silicon are studied using first-principles calculations in periodic supercells. Our results show that the V6 defect is the most stable among V1, V2 and V6 defects, and the V2-RB structure is a little more stable than the V2-LP structure due to lower vacancy formation energy. Furthermore, it is found that both V1 and V2 undergo the Jahn–Teller (JT) distortion while V6 does not. As a result, V1 and V2 have deep levels in the gap which mainly come from the neighboring atoms to vacancy. V6 has tailing bands in the gap, and so has a more stable electronic structure than V1 and V2. In addition, the JT distortion also reflects in the band decomposed charge density and the difference charge density.


2018 ◽  
Vol 20 (34) ◽  
pp. 21809-21813 ◽  
Author(s):  
M. Viswanathan

Single-crystal neutron diffraction reveals an enhancement of the guest-orderliness in a low-symmetric MOF, with an opposite scenario for its high-symmetric cousin. The mechanism behind this unusual effect is proposed.


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