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使用密度泛函缀加平面波法 ,按照能量最低原理采用共轭梯度方法对几种含铅空位和不含铅空位的钨酸铅晶体进行结构优化处理 ,计算了铅空位周围晶格的弛豫 ,得到铅空位周围的晶格结构 ,同时对计算结果进行了讨论 ;在得到几何优化结构的基础上 ,利用相对论性密度泛函离散变分法进一步计算了几种钨酸铅晶体结构的电子态密度 .计算结果表明 :1)铅空位周围的晶格驰豫的结果使铅空位的局部电负性减弱 .2 )Pb 6s态的能级位于离价带顶10eV左右 ,说明Pb 6s态上的电子很难再失去 ,所以在钨酸铅中不太可能存在Pb3+ 或Pb4 + .3)价带顶主要由O的 2p态占居 ,氧的 2p态最容易失去电子 .4 )铅空位周围的可能形成的色心是VF- VK+ 缔合色心 .
The density functional theory and plane wave method were used to optimize the structure of lead tungstate crystal with several lead-containing and lead-free vacancies using conjugate gradient method according to the lowest energy principle. The relaxation, The lattice structure around the lead vacancy was obtained and the calculation results were also discussed. Based on the geometrically optimized structure, the electronic density of states of several lead tungstate crystal structures were further calculated by using relativistic density functional discrete variational method The results show that: 1) The local electronegativity of Pb vacancy is weakened as a result of lattice relaxation around Pb vacancies.2) The energy level of Pb 6s state is about 10eV away from the top of the valence band, indicating that the electrons on Pb 6s state It is difficult to lose it, so Pb3 + or Pb4 + is unlikely to exist in lead tungstate.3) The top valence band is dominated by the 2p state of O, and the oxygen 2p state is the most likely to lose electrons.4) Possible lead vacancies The color center formed is VF-VK + association color center.