Title: Polarization spontaneous and piezo: fundamentals and their implementation in ab initio calculations Show Chinese title

Title: 极化自发和压电：基本原理及其在从头算计算中的实现

Abstract: Fundamental properties of spontaneous and piezo polarization are reformulated and critically reviewed. It was demonstrated that Landau definition of polarization as a dipole density could be used to the infinite systems. The difference between the bulk polarization and surface polarity are distinguished thus creating clear identification of both components. The local model of spontaneous polarization was created and used to calculate spontaneous polarization as the electric dipole density. It was shown that the proposed local model correctly predicts c-axis spontaneous polarization values of the nitride wurtzite semiconductors. It was also shown that the proposed model predicts zero polarization in the plane perpendicular to the c-axis, in accordance with symmetry requirements. In addition, the model results are in accordance with polarization equal to zero for zinc blende lattice. These data confirm the basic correctness of the proposed model. The spontaneous polarization values obtained for all wurtzite III nitrides (BN, AlN, GaN and InN) are in basic agreement with the earlier calculations using Berry phase and slab models of Bernardini et al. {Bernardini et al. Phys Rev B 56 (2001) R10024 & 63 (2001) 193201} but not with Dreyer et al. {Dreyer et al. Phys. Rev X 6 (2016) 021038}. Wurtzite nitride superlattices ab initio calculations were performed to derive polarization-induced fields in the coherently strained lattices showing good agreement with the polarization values. The strained superlattice data were used to determine the piezoelectric parameters of wurtzite nitrides obtaining the values that were in basic agreement with the earlier data. Zinc blende superlattices were also modeled using ab initio calculations showing results that are in agreement with the absence of polarization of all nitrides in zinc blende symmetry. Show Chinese abstract

Abstract: 自发极化和压电极化的基本性质被重新表述并进行了批判性回顾。 已经证明，Landau将极化定义为偶极子密度可以用于无限系统。 区分了体极化和表面极性，从而明确了两个分量的识别。 创建了自发极化的局部模型，并用于计算作为电偶极子密度的自发极化。 表明所提出的局部模型能够正确预测氮化物纤锌矿半导体的c轴自发极化值。 还表明，该模型在与c轴垂直的平面中预测零极化，这符合对称性要求。 此外，模型结果与闪锌矿结构的极化等于零一致。 这些数据证实了所提出模型的基本正确性。 对于所有纤锌矿III族氮化物（BN、AlN、GaN和InN）获得的自发极化值基本上与Bernardini等人使用Berry相和板模型的早期计算一致。 {Bernardini 等人 Phys Rev B 56 (2001) R10024 & 63 (2001) 193201}但与Dreyer等人不一致。 {Dreyer等 物理。 评论X 6 (2016) 021038}。 对纤锌矿氮化物超晶格进行了从头算计算，以推导共格应变晶格中的极化感应场，结果与极化值有良好一致性。 利用应变超晶格数据确定了纤锌矿氮化物的压电参数，得到的数值基本上与早期数据一致。 也使用从头算计算对闪锌矿超晶格进行了建模，结果与所有氮化物在闪锌矿对称性下无极化的现象一致。