论文标题
超越FröhlichHamiltonian：Anharmonic固体中大极性子的路径积分处理
Beyond the Fröhlich Hamiltonian: Path integral treatment of large polarons in anharmonic solids
论文作者
论文摘要
典型固体中电子的性质通过与晶体的相互作用进行了修改，从而导致式粒子的形成：北极子。通常使用FröhlichHamiltonian来描述这样的极性子，该北哈密顿量假定下面的晶格声子是谐波。但是，这种近似在几种有趣的材料中是无效的，包括最近发现的高压氢化物，在高于$ 200 $ k的温度下超导导。在本文中，我们表明可以扩展Fröhlich理论以消除此问题。我们在FröhlichHamiltonian中得出了四个额外的术语，以说明超高达三阶。我们使用扰动理论和Feynman的路径积分形式主义来计算新偏光元的能量和有效质量。结果表明，非谐的项会导致电子的显着额外捕获。由于其简单性和模型参数的数量很少，因此得出的哈密顿量非常适合分析计算。由于它是FröhlichHamiltonian的直接扩展，因此可以很容易地用于研究非谐性对其他极性特性的影响，例如光导率和双极性的形成。
The properties of an electron in a typical solid are modified by the interaction with the crystal ions, leading to the formation of a quasiparticle: the polaron. Such polarons are often described using the Fröhlich Hamiltonian, which assumes the underlying lattice phonons to be harmonic. However, this approximation is invalid in several interesting materials, including the recently discovered high-pressure hydrides which superconduct at temperatures above $200$K. In this paper, we show that Fröhlich theory can be extended to eliminate this problem. We derive four additional terms in the Fröhlich Hamiltonian to account for anharmonicity up to third order. We calculate the energy and effective mass of the new polaron, using both perturbation theory and Feynman's path integral formalism. It is shown that the anharmonic terms lead to significant additional trapping of the electron. The derived Hamiltonian is well-suited for analytical calculations, due to its simplicity and since the number of model parameters is low. Since it is a direct extension of the Fröhlich Hamiltonian, it can readily be used to investigate the effect of anharmonicity on other polaron properties, such as the optical conductivity and the formation of bipolarons.
