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运用以密度泛函理论为基础的相对论性离散变分方法(DV-Xα)模拟计算了完整的和含有F心、F+心以及F2心的碘化铯(CsI)晶体的电子结构,得到了含F心和F+心以及F2心的CsI晶体电子态密度分布以及它们可能产生的光学跃迁模式.计算结果表明,含F心和F2心的CsI晶体的禁带宽度明显变窄,F心和F2心的能级都出现在禁带中并且作为施主能级位于导带底部,利用过渡态理论计算得到其能级向Cs的5d轨道发生光学跃迁,能量跃迁值分别为1.69eV和1.15eV,该结果与实验结果完全一致,F+心没有能级出现在禁带中.计算结果从理论上成功地解释了碘化铯晶体经过辐照后电子型色心所产生的吸收带起源问题.
The electron structure of intact and CsI crystals containing F centers, F + centers and F2 centers was simulated using the relativistic discrete variational method (DV-Xα) based on density functional theory F centers and F2 centers, and their possible optical transition modes.The calculated results show that the band gap of CsI crystal with F-center and F2-center is obviously narrower, and the F-centers and F2-centers And the energy level is 1.69eV and 1.15eV, respectively. The results show that the energy levels of 5d orbitals of Cs are at 1.69eV and 1.15eV, respectively. Based on the transition state theory, The results are in good agreement with the experimental results, and the energy level of F + does not appear in the forbidden band.The calculated results successfully explain the origin of the absorption band produced by the electron-centered color centers of irradiated cesium iodide crystals theoretically.