Density Functional Approach to Study Electronic Structure of ZnO Single Crystal : LDA+U and GGA+U

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Density Functional Approach to Study Electronic Structure of ZnO Single Crystal : LDA+U and GGA+U

Post by Algerien1970 on Fri 22 May - 0:31



To download this article about the application of DFT+U method to study the ZnO single crysctal properties clik on the link below :



http://www.idosi.org/wasj/wasj14%2810%2911/13.pdf
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Re: Density Functional Approach to Study Electronic Structure of ZnO Single Crystal : LDA+U and GGA+U

Post by Algerien1970 on Thu 9 Jul - 11:33

Abstract:


In this paper, we have performed first-principles calculations of electronic and structural properties of ZnO in racksalt (B1), zincblende (B3) and wurtzite (B4) phases. The results for the electronic density of states (DOS) show that the lower part of the valence band is dominated by the O-2s orbital and the upper part by theO-2p orbital in ZnO. Also it is shown that the local-density approximation underestimates the band gap and misplaces the energy levels of the Zn-3d states. We have used the Engel-Vosko GGA formalism, which optimized the corresponding potential for band structure calculation of B1 and B3 phases. Typical errors incalculated band gaps originate from strong coulomb correlations, which are found to be highly significant inB4 phase. The LDA+U approach is found to correct the strong correlation of the Zn-3d electrons. The GGA+U approach is applied to Zn-3d and O-2p orbitals that cause to improve the band gap and correct the location ofZn-3d levels. Calculation of electron densi ty in three phases of ZnO in (110) plane is shown that this compoundhas ionic and covalent bond simultaneously. The calculations are in good agreement with the theoretical andexperimental values.
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