In this paper, a joint strategy was proposed to investigate the microscopic origin of the second-harmonic-generation (SHG) response in nonpolar ABCO₃F compounds. The SHG coefficients of ABCO₃F were evaluated using finite-field and sum-over-states methods. The tendency of the obtained SHG tensors is in good agreement with the powder SHG response. The atomic contribution was investigated using variation of the atomic charges and bandwidth of occupied atomic states. The results show that oxygen states play a key role in determining the SHG response, and the neighboring divalent cations exert a indirect influence via covalent interaction. The bidentate bonding pattern is beneficial to obtaining a largely enhanced SHG response.

中文翻译：

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评价非极性ABCO ₃ F化合物中二次谐波产生响应的微观起源的联合策略

在本文中，提出了一种联合策略来研究非极性ABCO ₃ F化合物中二次谐波产生（SHG）反应的微观起源。ABCO ₃ F的SHG系数使用有限域和求和状态法进行评估。获得的SHG张量的趋势与粉末SHG响应良好吻合。使用原子电荷的变化和所占据原子态的带宽研究了原子贡献。结果表明，氧状态在确定SHG反应中起关键作用，而相邻的二价阳离子通过共价相互作用产生间接影响。双齿结合模式有利于获得大大增强的SHG响应。