Saito and Oshiyama Reply:

Saito, Mineo; Oshiyama, Atsushi

doi:10.1103/physrevlett.74.4354

Cited by 90 publications

(148 citation statements)

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“…Also, Seong and Lewis found a RB configuration as the ground state structure for V 0 2 [5]. Although these calculations can explain the wave function character of the highest occupied state, the sense of the distortion is in disagreement with the experimental finding of rebonding by pairs [6,7]. In addition, the calculated energy difference between the RB configuration and the pairing configuration for V 2 2 was only 2.4 meV, much too small for a definite conclusion.…”

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confidence: 71%

“…In contrast with these experimental findings, theoretical calculations so far [2][3][4][5][6][7][8], which have mainly employed the ab initio plane-wave supercell technique with 64 atoms, have found a different JT distortion both in terms of the magnitude and the sense of the relaxation. For V 2 2 , Saito and Oshiyama found the atomic displacements opposite to the experimental finding [4] resulting in d 12 .…”

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confidence: 80%

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Large Pairing Jahn-Teller Distortions Around Divacancies in Crystalline Silicon

Öğüt

Chelikowsky

1999

Phys. Rev. Lett.

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Ab initio atomic and electronic structures of neutral ͑V 0 2 ͒ and charged ͑V 1 2 , V 2 2 , V 22 2 ͒ Si divacancies are investigated using bulk-terminated clusters with up to ഠ320 Si atoms. For the first time, the relaxed structures for V 1 2 , V 0 2 , and V 2 2 are found to exhibit large pairing Jahn-Teller distortions consistent with electron paramagnetic resonance experiments. Atomic relaxations, Jahn-Teller and relaxation energies, and hyperfine parameters are calculated for various charge states and compared with available experimental data. The cluster size and the anisotropic nature of the relaxations play key roles in establishing the stability of the structures with large pairing distortions. PACS numbers: 61.72.Ji, 71.55.CnSince the pioneering electron paramagnetic resonance (EPR) studies of Watkins and Corbett [1], there have been controversies about the electronic and atomic structures of the divacancy V 2 in crystalline Si. These controversies have revolved around the exact nature of the symmetrylowering Jahn-Teller (JT) distortions that split the degenerate deep levels. To date, the sense and the magnitude of these distortions, as inferred from the EPR data and theoretical calculations, have been at variance. This disagreement has created an ongoing debate for the ground state structures of V 2 in Si and presented a fundamental challenge to understanding this important semiconductor defect.The ideal simple divacancy, which is created by removing two neighboring Si atoms, has a D 3d symmetry and two doubly degenerate deep levels, labeled e u and e g (Fig. 1). While the e g level is empty, the lower e u level is occupied by one, two, and three electrons for the positively charged ͑V 1 2 ͒, neutral ͑V 0 2 ͒, and negatively charged ͑V 2 2 ͒ divacancies, respectively. As a result of this degeneracy, the lattice distorts to gain electronic energy. Upon symmetry lowering to C 2h , each e level splits into levels labeled a and b. Of these four levels, a g and b u have amplitudes, while a u and b g have nodes on the mirror plane of the C 2h distortion that contains the vacant sites and atoms 3 and 6 in Fig. 1(a). The ordering of these four levels inside the band gap depends on the particular sense and magnitude of the distortion.The EPR experiments of Watkins and Corbett indicated that V 1 2 and V 2 2 have the low symmetry of C 2h , and the highest occupied levels for both charge states have amplitudes on the mirror plane. They also established that the JT distortions occur in a pairing sense, which results in d 12 , d 13 d 23 , where d ij is the distance between atoms i and j [ Fig. 1(b)]. The JT energies E JT were estimated to be 1.3 eV and 2.4 eV for V 1 2 and V 2 2 , respectively. From these experimental findings, Watkins and Corbett concluded that the JT distortion had to be large enough for the a g level split from the upper e g level to be lowered below the a u level, as shown in Fig. 1(b). This would give configurations of V 1 2 :b 1 u (or a 1 g ) and V 2 2 :b 2 u a 1 g (or a 2 g b 1 u ), explaining ...

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confidence: 71%

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Large Pairing Jahn-Teller Distortions Around Divacancies in Crystalline Silicon

Öğüt

Chelikowsky

1999

Phys. Rev. Lett.

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“…In Ref. [5] it was shown that the difference between the radius of a neutron and a proton would grow with density and it was then claimed that this would lead to a violation of the Behrends-Sirlin-Ademollo-Gatto [6,7] (BSAG) theorem. This result, which was a consequence of an incorrect application of the constraint equations in the bag model, is wrong.…”

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confidence: 99%

Fermi matrix element with isospin breaking

2011

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Prompted by the level of accuracy now being achieved in tests of the unitarity of the CKM matrix, we consider the possible modification of the Fermi matrix element for the β-decay of a neutron, including possible in-medium and isospin violating corrections. While the nuclear modifications lead to very small corrections once the Behrends-Sirlin-Ademollo-Gatto theorem is respected, the effect of the u−d mass difference on the conclusion concerning V ud is no longer insignificant. Indeed, we suggest that the correction to the value of |V ud | 2 + |Vus| 2 + |V ub | 2 is at the level of 10 −4 .

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“…7,8 Also, the ab initio calculations by Seong and Lewis 5 give a resonant bond structure for V 2 0 (d 13 ϭd 23 Ͻd 12 : a u 2 ). These calculations are based on the density-functional theory ͑DFT͒ in the local-density ͑LD͒ approximation.…”

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confidence: 99%