Explanation of atomic displacement around lattice vacancies in diamond based on electron delocalization |
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Authors: | M Heidari Saani H Hashemi A Ranjbar M A Vesaghi A Shafiekhani |
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Institution: | 1.Semiconductor Component Industry,Tehran,Iran;2.Physics Group,Maleke Ashtar University,Shahin Shahr,Iran;3.Fachbereich Physik,Martin-Luther-Universit?t, Halle-Wittenberg,Halle,Germany;4.International Max Planck Research School for Science and Technology of Nanostructures, Weinberg 2,Halle,Germany;5.Department of Physics,Sharif University of Technology,Tehran,Iran;6.Department of Physics,Alzahra University,Vanak, Tehran,Iran |
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Abstract: | The relationship between unpaired electron delocalization and nearest-neighbor atomic relaxations in the vacancies of diamond
has been determined in order to understand the microscopic reason behind the neighboring atomic relaxation. The Density Functional
Theory (DFT) cluster method is applied to calculate the single-electron wavefunction of the vacancy in different charge states.
Depending on the charge and spin state of the vacancies, at outward relaxations, 84-90% of the unpaired electron densities
are localized on the first neighboring atoms. The calculated spin localizations on the first neighboring atoms in the ground
state of the negatively charged vacancy and in the spin quintet excited state of the neutral vacancy are in good agreement
with Electron Paramagnetic Resonance (EPR) measurements. The calculated spin localization of the positively charged vacancy
contrasts with the tentative assignment of the NIRIM-3 EPR signal to this center in (p-type) semiconductor diamond. The sign
of the lattice relaxation in the diamond vacancy is explained based on the effect of electron delocalization on nearest-neighbor
ion-ion screening, and also its effect on the bond length of neighboring atoms. |
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