Zhou Jin-Jian, Park Jinsoo, Timrov Iurii, Floris Andrea, Cococcioni Matteo, Marzari Nicola, Bernardi Marco
School of Physics, Beijing Institute of Technology, Beijing 100081, China.
Department of Applied Physics and Materials Science, California Institute of Technology, Pasadena, California 91125, USA.
Phys Rev Lett. 2021 Sep 17;127(12):126404. doi: 10.1103/PhysRevLett.127.126404.
Electron-phonon (e-ph) interactions are pervasive in condensed matter, governing phenomena such as transport, superconductivity, charge-density waves, polarons, and metal-insulator transitions. First-principles approaches enable accurate calculations of e-ph interactions in a wide range of solids. However, they remain an open challenge in correlated electron systems (CES), where density functional theory often fails to describe the ground state. Therefore reliable e-ph calculations remain out of reach for many transition metal oxides, high-temperature superconductors, Mott insulators, planetary materials, and multiferroics. Here we show first-principles calculations of e-ph interactions in CES, using the framework of Hubbard-corrected density functional theory (DFT+U) and its linear response extension (DFPT+U), which can describe the electronic structure and lattice dynamics of many CES. We showcase the accuracy of this approach for a prototypical Mott system, CoO, carrying out a detailed investigation of its e-ph interactions and electron spectral functions. While standard DFPT gives unphysically divergent and short-ranged e-ph interactions, DFPT+U is shown to remove the divergences and properly account for the long-range Fröhlich interaction, allowing us to model polaron effects in a Mott insulator. Our work establishes a broadly applicable and affordable approach for quantitative studies of e-ph interactions in CES, a novel theoretical tool to interpret experiments in this broad class of materials.
电子 - 声子（e - ph）相互作用在凝聚态物质中普遍存在，支配着诸如输运、超导、电荷密度波、极化子和金属 - 绝缘体转变等现象。第一性原理方法能够精确计算各种固体中的电子 - 声子相互作用。然而，在关联电子系统（CES）中，这仍然是一个开放的挑战，在这类系统中密度泛函理论常常无法描述基态。因此，对于许多过渡金属氧化物、高温超导体、莫特绝缘体、行星材料和多铁性材料，可靠的电子 - 声子计算仍然难以实现。在此，我们展示了在CES中电子 - 声子相互作用的第一性原理计算，使用哈伯德修正密度泛函理论（DFT + U）及其线性响应扩展（DFPT + U）框架，该框架能够描述许多CES的电子结构和晶格动力学。我们展示了这种方法对于典型莫特系统CoO的准确性，对其电子 - 声子相互作用和电子谱函数进行了详细研究。虽然标准的DFPT给出了不符合物理实际的发散且短程的电子 - 声子相互作用，但DFPT + U被证明能够消除这些发散，并正确考虑长程弗罗利希相互作用，使我们能够在莫特绝缘体中对极化子效应进行建模。我们的工作建立了一种广泛适用且经济实惠的方法，用于定量研究CES中的电子 - 声子相互作用，这是一种解释这类广泛材料中实验的新型理论工具。
