钼酸钙晶体中点缺陷的电子结构研究

Electronic structure of CaMoO_4 crystal with point defects

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氧空位的钼酸钙(CaMoO_4)晶体的电子结构,得到了含有F、F^+心的CaMoO_4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、F^+心的CaMoO_4晶体的禁带宽度明显变窄,F、F^+心的能级出现在禁带中,利用过渡态理论计算得到其向Mo的4 d轨道发生光学跃迁,跃迁能量值分别为1.93,2.03 eV.利用提拉法生长的CaMoO_4晶体呈现蓝色的本质原因是F、F^+心在黄红区产生比较强的吸收.

The electronic structures of CaMoO4 crystal with point defects are studied and numerically simulated on the basis of the framework of the fully relativistic self-consistent Direc-Slater theory. The numerical discrete variational （DV-Xα） method is used, which is based on the density function theory. The partial densities of states containing F,F^＋ color centers are obtained. The calculated resuits show that energy levels of F, F^＋ color centers occur in the forbidden band. Transition energies from the levels to the conduction band are 1.93 eV and 2.03 eV, respectively. The calculated results explain the fact that the CaMoO4 crystal formed by Czochralski growth method will exhibit blue color.