Hu Yue, Zhu Zhen, Xiao Jiamin, Shao Hezhu, Zhao Li, Xu Min, Zhuang Jun
Shanghai Ultra Precision Optical Manufacturing Engineering Technology Research Center, Department of Optical Science and Engineering, Fudan University, Shanghai, 200433, China.
Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences, Ningbo, 315201, China.
Sci Rep. 2019 Jul 18;9(1):10399. doi: 10.1038/s41598-019-46672-0.
We carried out ab initio calculations to study the atomic configuration, band structure and optical absorption of the lattice misalignment structure (LMS) in a subsurface layer of a machined KHPO (KDP) crystal. By varying the different degrees of misalignment, the changes in the corresponding atomic position and bond and energy are obtained, and their correlations are analysed in detail. The results indicate that in the LMS evolution, the variation in the proton distribution around the oxygen atoms plays an important role, and many local stable LMSs appear. Interestingly, at a certain misalignment value, the total system energy of the local stable LMS is near that of a perfect KDP crystal. For some local stable LMSs, the electronic and optical properties related to the laser damage threshold (LDT) of KDP are further studied. The results show that in comparison with a perfect KDP crystal, the band gaps of local stable LMSs at some certain misalignment values become narrow, and their optical absorption curves produce an obvious redshift. These facts demonstrate that the emergence of the LMS could have a significant impact on the optical absorption of the KDP material and thus affect the LDT of KDP under certain working conditions.
我们进行了从头算计算，以研究加工后的KHPO（KDP）晶体表面下一层中晶格失配结构（LMS）的原子构型、能带结构和光吸收。通过改变不同程度的失配，获得了相应原子位置、键和能量的变化，并对它们之间的相关性进行了详细分析。结果表明，在LMS演化过程中，氧原子周围质子分布的变化起着重要作用，并且出现了许多局部稳定的LMS。有趣的是，在某个失配值下，局部稳定LMS的总系统能量接近完美KDP晶体的总系统能量。对于一些局部稳定的LMS，进一步研究了与KDP激光损伤阈值（LDT）相关的电子和光学性质。结果表明，与完美KDP晶体相比，在某些特定失配值下局部稳定LMS的带隙变窄，并且它们的光吸收曲线产生明显的红移。这些事实表明，LMS的出现可能会对KDP材料的光吸收产生重大影响，从而在某些工作条件下影响KDP的LDT。
