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arXiv 2109.00554cond-mat.mtrl-scicond-mat.mes-hallcond-mat.str-elquant-ph
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DFT随机相位近似与低能有效模型的光学响应比较:应变磷

Comparison of Optical Response from DFT Random Phase Approximation and Low-Energy Effective Model: Strained Phosphorene

Mohammad Alidoust, Erlend E. Isachsen, Klaus Halterman, Jaakko Akola

摘要:

材料的光学响应工程是一个需要微观精度和可靠的预测理论工具的范例。在这里,我们比较和对比的色散介电常数张量,使用低能量有效模型和密度泛函理论(DFT)。作为一种代表性的材料,磷受到应变被认为是。采用低能模型哈密顿量和格林函数电流-电流关联函数,我们计算了动态光电导率及其相关的介电常数张量。对于DFT方法,第一性原理计算利用一阶随机相位近似。我们的研究结果表明,虽然这两个模型是在低应变和低频率范围内的协议,复杂的功能与系统和光电子器件实现的基本物理特性,如带隙,Drude吸收响应,消失实部,吸收率和符号的介电常数在频率范围内显示显着的差异。我们的研究结果表明,广泛使用的DFT软件包中采用的随机相位近似应重新审视和改进,以便能够预测这些基本的电子特性的给定材料的信心。此外,采用这两种模型的介电常数的结果,我们发现磷烯可以在光电子器件中发挥的关键作用,以促进高度可编程的完美吸收的电磁波通过操纵化学势和施加应变,并说明如何可靠的预测给定材料的介电响应是至关重要的精确的设备设计。

英文摘要:

The engineering of the optical response of materials is a paradigm that demands microscopic-level accuracy and reliable predictive theoretical tools. Here we compare and contrast the dispersive permittivity tensor, using both a low-energy effective model and density functional theory (DFT). As a representative material, phosphorene subject to strain is considered. Employing a low-energy model Hamiltonian with a Green's function current-current correlation function, we compute the dynamical optical conductivity and its associated permittivity tensor. For the DFT approach, first-principles calculations make use of the first-order random-phase approximation. Our results reveal that although the two models are generally in agreement within the low-strain and low-frequency regime, the intricate features associated with the fundamental physical properties of the system and optoelectronic device implementation such as band gap, Drude absorption response, vanishing real part, absorptivity, and sign of permittivity over the frequency range show significant discrepancies. Our results suggest that the random-phase approximation employed in widely used DFT packages should be revisited and improved to be able to predict these fundamental electronic characteristics of a given material with confidence. Furthermore, employing the permittivity results from both models, we uncover the pivotal role that phosphorene can play in optoelectronics devices to facilitate highly programable perfect absorption of electromagnetic waves by manipulating the chemical potential and exerting strain and illustrate how reliable predictions for the dielectric response of a given material are crucial to precise device design.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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