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Electron Localization (electron + localization)

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Physics and Astronomy50%

Terms modified by Electron Localization

  • electron localization function
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    Selected Abstracts

    Electron localization and the second moment of the exchange hole,

    INTERNATIONAL JOURNAL OF QUANTUM CHEMISTRY, Issue 11 2009
    J. G. ÁngyánArticle first published online: 16 APR 200
    Abstract The localization tensor, which is a global measure of the itinerant character of the electrons, has been defined by Resta as the second cumulant moment of the position operator per electron. It seems to be a meaningful parameter not only for solids but also for finite molecular systems. In the independent-particle limit, this quantity can be interpreted as the density-weighted average of the second moment of the exchange hole. After examining several possible local measures based on the moment analysis of the exchange hole, it turns out that the density weighted squared exchange hole dipole moment might be a useful local indicator of electron localization. © 2009 Wiley Periodicals, Inc. Int J Quantum Chem, 2009 [source]

    Electron localization and emission mechanism in wurtzite (Al, In, Ga)N alloys

    PHYSICA STATUS SOLIDI (B) BASIC SOLID STATE PHYSICS, Issue 1 2010
    Qihang Liu
    Abstract The electronic structures of wurtzite InGaN and AlGaN alloys are investigated using the first-principle density functional theory calculation. The results indicate that some short In,N,In atomic chains and small In,N atomic condensates composed of a few In and N atoms can be randomly formed in InGaN alloys. The electrons at the top of valence bands can be effectively localized in the vicinity of the In,N,In zigzag chains (weak localization) and the In,N atomic condensates (strong localization). These localized electrons extremely enhance the emission efficiency of InGaN alloys. [source]

    Electron localization in an external electric field

    PHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 1 2004
    O. Bleibaum
    Abstract The impact of a weak electric field on the weak-localization corrections is studied within the framework of a nonlinear , -model. Two scaling regimes are obtained. In one, the scaling is dominated by temperature; in the other, by the electric field. An explicit expression is derived for the crossover temperature between the two regimes. (© 2003 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]

    Thomas,Fermi approximation for the quasi-two-dimensional electron gas

    INTERNATIONAL JOURNAL OF QUANTUM CHEMISTRY, Issue 6 2001
    M. Moreno
    Abstract To take into account static correlation effects in the quasi-two-dimensional electron gas a screened Coulombic interaction between particles is studied. The Thomas,Fermi approximation is used and the potential screening appears as a function of the Wigner,Seitz density parameter rs and the effective width t of the system. With the self-consistent field theory applied to the modified deformable jellium, the ground-state energy per particle and the conditions for electron localization are obtained in terms of the interparticle distance and the screening parameter ,. A critical minimum characteristic width tc is obtained; below tc no long-range order is obtained. For larger widths a stable localized state is predicted at finite densities. © 2001 John Wiley & Sons, Inc. Int J Quant Chem 82: 269,276, 2001 [source]

    Bound electronic states on a dislocation kink in semiconductors

    PHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 8 2007
    Robert A. Vardanyan
    Abstract We discuss electron localization on dislocation kinks, that is essential for multiphonon capture of carriers by the dislocation, in view of the problem of recombination-enhanced defect glide in wide-band semiconductors. In the case of a smooth kink (when the continuum model is applicable) the formation of bound electronic states is analyzed analytically. The eigenstates and corresponding wave functions are found, depending both on kink parameters and electronic characteristics of the semiconductor. A possible application of the obtained results for the analysis of electron localization on an abrupt kink is considered. (© 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]

    Theory of chemical bonds in metalloenzymes.

    INTERNATIONAL JOURNAL OF QUANTUM CHEMISTRY, Issue 15 2010

    Abstract Reaction mechanisms of oxygen evolution in native and artificial photosynthesis II (PSII) systems have been investigated on the theoretical grounds, together with experimental results. First of all, our previous broken-symmetry (BS) molecular orbitals (MO) calculations are reviewed to elucidate the instability of the d,-p, bond in high-valent (HV) Mn(X)O systems and the d,-p,-d, bond in HV MnOMn systems. The triplet instability of these bonds entails strong or intermediate diradical characters: ,Mn(IV)O, and ,MnOMn,; the BS MO resulted from strong electron correlation, leading to the concept of electron localizations and local spins. The BS computations have furthermore revealed guiding principles for derivation of selection rules for radical reactions of local spins. As a continuation of these theoretical results, the BS MO interaction diagrams for oxygen-radical coupling reactions in the oxygen evolution complex (OEC) in the PSII have been depicted to reveal scope and applicability of local singlet diradical (LSD) and local triplet diradical (LTD) mechanisms that have been successfully utilized for theoretical understanding of oxygenation reactions mechanisms by p450 and methane monooxygenase (MMO). The manganese-oxide cluster models examined are London, Berlin, and Berkeley models of CaMn4O4 and related clusters Mn4O4 and Mn3Ca. The BS MO interaction diagrams have revealed the LSD and/or LTD mechanisms for generation of molecular oxygen in the total low-, intermediate and high-spin states of these clusters. The spin alignments are found directly corresponding to the spin-coupling mechanisms of oxygen-radical sites in these clusters. The BS UB3LYP calculations of the clusters have been performed to confirm the comprehensive guiding principles for oxygen evolution; charge and spin densities by BS UB3LYP are utilized for elucidation and confirmation of the LSD and LTD mechanisms. Applicability of the proposed selection rules are examined in comparison with a lot of accumulated experimental and theoretical results for oxygen evolution reactions in native and artificial PSII systems. © 2010 Wiley Periodicals, Inc. Int J Quantum Chem, 2010 [source]