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arXiv 1703.02496cond-mat.mtrl-sci
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Hubbard项修正对纤锌矿Zn结构参数和电子性质的影响

Effects of Hubbard term correction on the structural parameters and electronic properties of wurtzite Zn

E. S. Goh, J. W. Mah, T. L. Yoon

摘要:

研究了Hubbard在位库仑修正对纤锌矿ZnO结构参数和价能态的影响。由于Znd态和Op态杂化修正引起的结构参数的变化,必须确定合适的Hubbard项参数才能准确预测ZnO的性质。采用LDA+ ${U}$方法,对Zn 3d态和O 2 p态分别采用$U_p$和$U_p$进行Hubbard修正,结果表明,所有Hubbard参数都低估了晶格常数. $U_d$和$U_p$修正项的结合使得纤锌矿ZnO的禁带宽度达到了实验值。除了预测准确的带隙值之外,还选择具有d带的正确定位和准确带宽的成对的$U_p$和$U_p$参数。然而,振动特性的检查,发现估计的伽马声子频率和实验值之间的不匹配。在LDA+ ${U}$计算中,仅根据电子能带性质选择Hubbard项不能保证振动描述的准确性.

英文摘要:

The effects of including the Hubbard on-site Coulombic correction to the structural parameters and valence energy states of wurtzite ZnO was explored. Due to the changes in the structural parameters caused by correction of hybridization between Zn d states and O p states, suitable parameters of Hubbard terms have to be determined for an accurate prediction of ZnO properties. Using the LDA+${U}$ method by applying Hubbard corrections $U_p$ to Zn 3d states and $U_p$ to O 2p states, the lattice constants were underestimated for all tested Hubbard parameters. The combination of both $U_d$ and $U_p$ correction terms managed to widen the band gap of wurtzite ZnO to the experimental value. Pairs of $U_p$ and $U_p$ parameters with the correct positioning of d-band and accurate bandwidths were selected, in addition to predicting an accurate band gap value. Inspection of vibrational properties, however, revealed mismatches between the estimated gamma phonon frequencies and experimental values. The selection of Hubbard terms based on electronic band properties alone cannot ensure an accurate vibrational description in LDA+${U}$ calculation.

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