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介绍了一种基于从头计算的DV-Xα方法和有效哈密顿量模型,它可以计算晶体中掺杂离子的晶体场参数和旋轨耦合参数,尤其适合计算低对称性的晶体.对于低对称性的晶体,参数的数目比能级的数目多,因此通过实验能级拟合确定所有的参数不太准确,而从头计算法可以准确地确定所有的晶体场参数和旋轨耦合参数.首先用这种模型计算了Yb3+掺杂GdTaO4晶体中的晶体场参数和旋轨耦合参数,然后给出了Yb3+在GdTaO4中的能级结构,并分析了Yb3+:GdTaO4的发射谱形成一个连续的发射带.这有利于激光的调谐和锁模激光输出,预言了Yb3+:GdTaO4有望成为新型全固态超短脉冲激光工作物质.同样用这种模型分别计算了Yb3+掺杂YTaO4和ScTaO4中的晶体场参数和旋轨耦合参数,并给出了Yb3+在YTaO4和ScTaO4中的能级结构,得到了与Yb3+:GdTaO4晶体类似的结论.
A DV-Xα method based on ab initio method and an effective Hamiltonian model are introduced, which can calculate the crystal field parameters and spin-orbit coupling parameters of doped ions in crystal, and are especially suitable for the calculation of low-symmetry crystals. Of the crystal, the number of parameters than the number of levels, so the experimental level fitting to determine all the parameters are not accurate, and ab initio method can accurately determine all the crystal field parameters and the coupling parameters of the swing. The crystal model and spin-orbit coupling parameters of Yb3 + -doped GdTaO4 crystal were calculated, and then the energy level structure of Yb3 + in GdTaO4 was given, and the emission spectra of Yb3 +: GdTaO4 were analyzed to form a continuous emission band. Is conducive to the laser tuning and mode-locked laser output, predicted Yb3 +: GdTaO4 is expected to become a new all-solid-state ultrashort pulse laser work material.Also use this model were calculated Yb3 + doped YTaO4 and ScTaO4 crystal field parameters and the spiral Coupling parameters, and gives the energy level structure of Yb3 + in YTaO4 and ScTaO4. The conclusion is similar to that of Yb3 +: GdTaO4 crystals.