Sui Tingting, Lian Yafei, Xu Mingxia, Zhang Lisong, Li Yanlu, Zhao Xian, Sun Xun
State Key Laboratory of Crystal Materials, Shandong University Jinan 250100 China
RSC Adv. 2018 Feb 12;8(13):6931-6939. doi: 10.1039/c7ra13212c. eCollection 2018 Feb 9.
The formation energies, charge transition levels, and electronic structures of positively charged, neutral, and negatively charged hydrogen vacancies in the NHHPO (ADP) crystal are investigated in the framework of density functional theory with local and hybrid exchange-correlation functionals. The inclusion of nonlocal exchange opens the ADP fundamental band gap by nearly 1 eV and well reproduces the experimental value. The van der Waals (vdW) interaction is found to have a major influence on the energetics of charged hydrogen vacancies in ADP. The calculated relative stability of and with vdW interaction could well explain the break point on the measured conductivity curve of the ADP crystal in the high temperature region. On the other hand, a missing H atom in the (HPO) group is found to be more energetically preferable than NH . It could capture a hole carrier to form a molecular-type polaron with its adjacent two O atoms, and be responsible for the optical absorption under irradiation by a high-intensity laser beam.
在密度泛函理论框架下，使用局域和杂化交换关联泛函研究了NHHPO（ADP）晶体中带正电、中性和带负电的氢空位的形成能、电荷转移能级和电子结构。包含非局域交换使ADP的基本带隙打开近1 eV，并很好地再现了实验值。发现范德华（vdW）相互作用对ADP中带电氢空位的能量学有重大影响。计算得到的有vdW相互作用时的相对稳定性可以很好地解释ADP晶体在高温区域测量的电导率曲线上的断点。另一方面，发现（HPO）基团中缺少一个H原子在能量上比NH更有利。它可以捕获一个空穴载流子，与相邻的两个O原子形成分子型极化子，并在高强度激光束照射下负责光吸收。
