论文标题
不均匀晶体的电化
Electric Polarization in Inhomogeneous Crystals
论文作者
论文摘要
我们使用基于波数据包方法的半经典粗晶粒程序将电荷密度得出不均匀晶体的空间梯度中的二阶。它可以重现为极化的差异，其一阶贡献由三个部分组成，对原始浆果连接表达式的扰动校正，拓扑零件可以写成Chern-simons 3型的积分，以及以前未知的四核酸杆菌样的贡献。拓扑部分可能与涡流在二维系统中携带的量化分数有关。然后，我们将结果概括为多波段案例，并表明类似四极的贡献起着重要作用，因为它使总偏振量规无关。最后，我们在多个模型系统中验证我们的理论。
We derive the charge density up to second order in spatial gradient in inhomogeneous crystals using the semiclassical coarse graining procedure based on the wave packet method. It can be recast as divergence of polarization, whose first-order contribution consists of three parts, a perturbative correction to the original Berry connection expression, a topological part that can be written as an integral of the Chern-Simons 3-form, and a previously-unknown, quadrupole-like contribution. The topological part can be related to the quantized fractional charge carried by a vortex in two dimensional systems. We then generalize our results to the multi-band case and show that the quadrupole-like contribution plays an important role, as it makes the total polarization gauge-independent. Finally, we verify our theory in several model systems.
