Dreyer Cyrus E, Coh Sinisa, Stengel Massimiliano
Department of Physics and Astronomy, Stony Brook University, Stony Brook, New York, 11794-3800, USA.
Center for Computational Quantum Physics, Flatiron Institute, 162 5th Avenue, New York, New York 10010, USA.
Phys Rev Lett. 2022 Mar 4;128(9):095901. doi: 10.1103/PhysRevLett.128.095901.
In insulators, Born effective charges describe the electrical polarization induced by the displacement of individual atomic sublattices. Such a physical property is at first sight irrelevant for metals and doped semiconductors, where the macroscopic polarization is ill defined. Here we show that, in clean conductors, going beyond the adiabatic approximation results in nonadiabatic Born effective charges that are well defined in the low-frequency limit. In addition, we find that the sublattice sum of the nonadiabatic Born effective charges does not vanish as it does in the insulating case, but instead is proportional to the Drude weight. We demonstrate these formal results with density functional perturbation theory calculations of Al and electron-doped SnS_{2} and SrTiO_{3}.
在绝缘体中，玻恩有效电荷描述了由单个原子子晶格位移引起的电极化。乍一看，这种物理性质与金属和掺杂半导体无关，因为在金属和掺杂半导体中宏观极化的定义不明确。在这里，我们表明，在纯净导体中，超越绝热近似会导致在低频极限下定义明确的非绝热玻恩有效电荷。此外，我们发现非绝热玻恩有效电荷的子晶格总和不像在绝缘情况下那样为零，而是与德鲁德权重成正比。我们通过对铝以及电子掺杂的二硫化锡和钛酸锶进行密度泛函微扰理论计算来证明这些形式上的结果。
