非线性光学晶体NaRbMgP₂O₇氧空位性质的理论研究

Theoretical study on the vacancy properties of nonlinear optical crystal NaRbMgP₂O₇ Oxygen

摘要

运用第一性原理计算了非线性光学晶体NaRbMgP₂O₇中氧空位的形成能、中性氧空位和正电态下的局部结构特征与电子结构性质。结果显示，中性氧空位的形成能为3.28eV.氧空位的引入对焦磷酸根基团中的原子产生了不同的影响。在中性态下，体系多余两个电子，氧空位最近邻的P原子俘获近一个电子，另一个电子主要分布在氧空位处，而对氧空位次近邻的P原子影响较小，中性态下氧空位在带隙中引入了占据的缺陷态，导致能隙降低了约1.1 eV.+1电荷态下，占据的缺陷态减少，+2电荷态下，占据的缺陷态消失，带隙中形成新的未占据的缺陷态。

Abstract

The formation energy of oxygen vacancy in nonlinear optical crystal NaRbMgP₂O₇, the local structure characteristics and electronic structure properties in neutral oxygen vacancy and positive state have been calculated by using first principles. The results show that the formation energy of neutral oxygen vacancy is 3.28eV. The introduction of oxygen vacancy has different effects on the atoms in the pyrophosphate base group. In the neutral state, there are more than two electrons in the system, the P atom of the nearest oxygen vacancy captures nearly one electron, and the other electron is mainly distributed in the oxygen vacancy, and has little influence on the P atom of the second nearest oxygen vacancy. In the neutral state, the oxygen vacancy introduces occupied defect states into the band gap, resulting in a decrease in the energy gap of about 1.1 eV.+1 charge state, the occupied defect states are reduced, and +2 charge state, the occupied defect states disappear, and new unoccupied defect states are formed in the band gap.

关键词

非线性光学晶体 / NaRbMgP₂O₇ / 氧空位 / 第一性原理

Key words

nonlinear optical crystal / NaRbMgP₂O₇ / Oxygen vacancy / First principle

参考文献

[1] W. Wang, D. Mei, S. Wen, J. Wang, Y. J.C.C.L. Wu, Complex coordinated functional groups: A great genes for nonlinear optical materials, 33 ( 2022) 2301-2315.

[2] S. Zhao, X. Yang, Y. Yang, X. Kuang, F. Lu, P. Shan, Z. Sun, Z. Lin, M. Hong, J. Luo, Non-Centrosymmetric RbNaMgP₂O₇ with Unprecedented Thermo-Induced Enhancement of Second Harmonic Generation, J Am Chem Soc, 140 ( 2018) 1592-1595.

[3] P. E Blöchl. Projector augmented-wave method[J]. Phys. Rev. B, 50( 1994), 17953-17979.

[4] J P Perdew, K Burke, M. Ernzerhof Generalized gradient approximation made simple[J]. Physical review letters, 77:18( 1996): 3865.

[5] H. Monkhorst, J. Pack, Special points for Brillouin-zone integrations[J]. Phys. Rev. B, 13( 1976) 5188.

[6] C.S. Liu, C. J. Hou, N. Kioussis, S. G. Demos, H.B. Radousky, Electronic structure calculations of an oxygen vacancy in KH₂PO₄, Phys.Rev.B, 72 ( 2005) 134110.